U.S. patent application number 14/869152 was filed with the patent office on 2016-04-28 for flexible multiplexing and feedback for variable transmission time intervals.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Arumugam Chendamarai Kannan, Aleksandar Damnjanovic, Jelena Damnjanovic, Tao Luo, Durga Prasad Malladi, Siddhartha Mallik, Madhavan Srinivasan Vajapeyam, Yongbin Wei, Taesang Yoo.
Application Number | 20160119948 14/869152 |
Document ID | / |
Family ID | 54325076 |
Filed Date | 2016-04-28 |
United States Patent
Application |
20160119948 |
Kind Code |
A1 |
Damnjanovic; Jelena ; et
al. |
April 28, 2016 |
FLEXIBLE MULTIPLEXING AND FEEDBACK FOR VARIABLE TRANSMISSION TIME
INTERVALS
Abstract
Methods, systems, and devices for wireless communication are
described. A base station may employ a multiplexing configuration
based on latency and efficiency considerations. The base station
may transmit a resource grant, a signal indicating the length of a
downlink (DL) transmission time interval (TTI), and a signal
indicating the length of a subsequent uplink (UL) TTI to one or
more user equipment (UEs). The base station may dynamically select
a new multiplexing configuration by, for example, setting the
length of an UL TTI to zero or assigning multiple UEs resources in
the same DL TTI. Latency may also be reduced by employing block
feedback, such as block hybrid automatic repeat request (HARQ)
feedback. A UE may determine and transmit HARQ feedback for each
transport block (TB) of a set of TBs, which may be based on a time
duration of a downlink TTI.
Inventors: |
Damnjanovic; Jelena; (Del
Mar, CA) ; Yoo; Taesang; (Riverside, CA) ;
Mallik; Siddhartha; (San Diego, CA) ; Damnjanovic;
Aleksandar; (Del Mar, CA) ; Chendamarai Kannan;
Arumugam; (San Diego, CA) ; Vajapeyam; Madhavan
Srinivasan; (San Diego, CA) ; Malladi; Durga
Prasad; (San Diego, CA) ; Wei; Yongbin; (La
Jolla, CA) ; Luo; Tao; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
54325076 |
Appl. No.: |
14/869152 |
Filed: |
September 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62068416 |
Oct 24, 2014 |
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62075624 |
Nov 5, 2014 |
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Current U.S.
Class: |
370/280 |
Current CPC
Class: |
H04W 72/14 20130101;
H04L 5/0044 20130101; H04L 5/0094 20130101; H04L 1/1812 20130101;
H04W 72/1289 20130101; H04L 5/0055 20130101; H04L 5/14 20130101;
H04W 72/1294 20130101 |
International
Class: |
H04W 72/12 20060101
H04W072/12; H04L 1/18 20060101 H04L001/18; H04L 5/14 20060101
H04L005/14 |
Claims
1. A method of wireless communication comprising: identifying a
downlink transmission time interval (TTI) of a time-division duplex
(TDD) configured carrier; receiving an indication of a duration of
the downlink TTI during the downlink TTI; receiving an indication
of a duration of an uplink TTI that follows the downlink TTI,
wherein the indication of the duration of the uplink TTI is
received during the downlink TTI; and communicating based at least
in part on the indication of the duration of the downlink TTI and
the indication of the duration of the uplink TTI.
2. The method of claim 1, further comprising: receiving a downlink
grant during the downlink TTI, wherein the downlink grant assigns a
first set of resources during the downlink TTI.
3. The method of claim 2, further comprising: receiving an
indication of a duration of a subsequent downlink TTI that follows
the downlink TTI, wherein the indication of the duration of the
subsequent downlink TTI is received during the subsequent downlink
TTI; receiving an indication of a duration of a subsequent uplink
TTI that follows the subsequent downlink TTI, wherein the
indication of the duration of the subsequent uplink TTI is received
during the subsequent downlink TTI; and communicating based at
least in part on the indication of the duration of the subsequent
downlink TTI and the indication of the duration of the subsequent
uplink TTI.
4. The method of claim 1, wherein the indication of the duration of
the uplink TTI indicates that the duration of the uplink TTI is
zero.
5. The method of claim 4, wherein the duration of the downlink TTI
and a duration of a subsequent downlink TTI form a downlink burst
that is time division multiplexed on resources of the TDD
configured carrier.
6. The method of claim 1, wherein the communicating comprises:
receiving a set of transport blocks (TBs) during the downlink TTI,
wherein the downlink TTI comprises a variable TTI; determining
hybrid automatic repeat request (HARQ) feedback for each TB of the
set of TBs, wherein a number of TBs in the set of TBs is based at
least in part on the duration of the downlink TTI; and transmitting
the HARQ feedback for at least one TB of the set of TBs during the
uplink TTI.
7. The method of claim 6, further comprising: determining HARQ
feedback for a number of code blocks (CBs), wherein each TB of the
set of TBs comprises at least one CB, and wherein a quantity of CBs
in each TB is based at least in part on a size of each TB; and
transmitting the HARQ feedback for the number of CBs during the
uplink TTI.
8. The method of claim 1, further comprising: entering a low power
state during the downlink TTI or the uplink TTI based at least in
part on an absence of a grant of resources during the downlink TTI
or the uplink TTI.
9. An apparatus for wireless communication comprising: means for
identifying a downlink transmission time interval (TTI) of a
time-division duplex (TDD) configured carrier; means for receiving
an indication of a duration of the downlink TTI during the downlink
TTI; means for receiving an indication of a duration of an uplink
TTI that follows the downlink TTI, wherein the indication of the
duration of the uplink TTI is received during the downlink TTI; and
means for communicating based at least in part on the indication of
the downlink TTI and the indication of the uplink TTI.
10. The apparatus of claim 9, further comprising: means for
receiving a downlink grant during the downlink TTI, wherein the
downlink grant assigns a first set of resources during the downlink
TTI.
11. The apparatus of claim 10, further comprising: means for
receiving an indication of a duration of a subsequent downlink TTI
that follows the downlink TTI, wherein the indication of the
duration of the subsequent downlink TTI is received during the
subsequent downlink TTI; means for receiving an indication of a
duration of a subsequent uplink TTI that follows the subsequent
downlink TTI, wherein the indication of the duration of the
subsequent uplink TTI is received during the subsequent downlink
TTI; and means for communicating based at least in part on the
indication of the duration of the subsequent downlink TTI and the
indication of the duration of the subsequent uplink TTI.
12. The apparatus of claim 9, wherein the indication of the
duration of the uplink TTI indicates that the duration of the
uplink TTI is zero.
13. The apparatus of claim 12, wherein the duration of the downlink
TTI and a duration of a subsequent downlink TTI form a downlink
burst that is time division multiplexed on resources of the TDD
configured carrier.
14. The apparatus of claim 9, wherein the means for communicating
comprises means for receiving a set of transport blocks (TBs)
during the downlink TTI, wherein the downlink TTI comprises a
variable TTI, and wherein the apparatus further comprises: means
for determining hybrid automatic repeat request (HARQ) feedback for
each TB of the set of TBs, wherein a number of TBs in the set of
TBs is based at least in part on the duration of the downlink TTI;
and means for transmitting the HARQ feedback for at least one TB of
the set of TBs during the uplink TTI.
15. The apparatus of claim 14, further comprising: means for
determining HARQ feedback for a number of code blocks (CBs),
wherein each TB of the set of TBs comprises at least one CB, and
wherein a quantity of CBs in each TB is based at least in part on a
size of each TB; and means for transmitting the HARQ feedback for
the number of CBs during the uplink TTI.
16. The apparatus of claim 9, further comprising: means for
entering a low power state during the downlink TTI or the uplink
TTI based at least in part on an absence of a grant of resources
during the downlink TTI or the uplink TTI.
17. An apparatus for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
and instructions stored in the memory and operable, when executed
by the processor, to cause the apparatus to: identify a downlink
transmission time interval (TTI) of a time-division duplex (TDD)
configured carrier; receive an indication of a duration of the
downlink TTI during the downlink TTI; receive an indication of a
duration of an uplink TTI that follows the downlink TTI, wherein
the indication of the duration of the uplink TTI is received during
the downlink TTI; and communicate based at least in part on the
indication of the duration of the downlink TTI and the indication
of the duration of the uplink TTI.
18. The apparatus of claim 17, wherein the instructions are
operable to cause the apparatus to: receive a downlink grant during
the downlink TTI, wherein the downlink grant assigns a first set of
resources during the downlink TTI.
19. The apparatus of claim 18, wherein the instructions are
operable to cause the apparatus to: receive an indication of a
duration of a subsequent downlink TTI that follows the downlink
TTI, wherein the indication of the duration of the subsequent
downlink TTI is received during the subsequent downlink TTI;
receive an indication of a duration of a subsequent uplink TTI that
follows the subsequent downlink TTI, wherein the indication of the
duration of the subsequent uplink TTI is received during the
subsequent downlink TTI; and communicate based at least in part on
the indication of the duration of the subsequent downlink TTI and
the indication of the duration of the subsequent uplink TTI.
20. The apparatus of claim 17, wherein the indication of the
duration of the uplink TTI indicates that the duration of the
uplink TTI is zero.
21. The apparatus of claim 20, wherein the duration of the downlink
TTI and a duration of a subsequent downlink TTI form a downlink
burst that is time division multiplexed on resources of the TDD
configured carrier.
22. The apparatus of claim 17, wherein the instructions are
operable to cause the apparatus to: receive a set of transport
blocks (TBs) during the downlink TTI, wherein the downlink TTI
comprises a variable TTI; determine hybrid automatic repeat request
(HARQ) feedback for each TB of the set of TBs, wherein a number of
TBs in the set of TBs is based at least in part on the duration of
the downlink TTI; and transmit the HARQ feedback for at least one
TB of the set of TBs during the uplink TTI.
23. The apparatus of claim 22, wherein the instructions are
operable to cause the apparatus to: determine HARQ feedback for a
number of code blocks (CBs), wherein each TB of the set of TBs
comprises at least one CB, and wherein a quantity of CBs in each TB
is based at least in part on a size of each TB; and transmit the
HARQ feedback for the number of CBs during the uplink TTI.
24. The apparatus of claim 17, wherein the instructions are
operable to cause the apparatus to: enter a low power state during
the downlink TTI or the uplink TTI based at least in part on an
absence of a grant of resources during the downlink TTI or the
uplink TTI.
25. A non-transitory computer-readable medium storing code for
wireless communication, the code comprising instructions executable
to: identify a downlink transmission time interval (TTI) of a
time-division duplex (TDD) configured carrier; receive an
indication of a duration of the downlink TTI during the downlink
TTI; receive an indication of a duration of an uplink TTI that
follows the downlink TTI, wherein the indication of the duration of
the uplink TTI is received during the downlink TTI; and communicate
based at least in part on the indication of the duration of the
downlink TTI and the indication of the duration of the uplink
TTI.
26. The non-transitory computer-readable medium of claim 25,
wherein the instructions are executable to: receive a downlink
grant during the downlink TTI, wherein the downlink grant assigns a
first set of resources during the downlink TTI.
27. The non-transitory computer-readable medium of claim 26,
wherein the instructions are executable to: receive an indication
of a duration of a subsequent downlink TTI that follows the
downlink TTI, wherein the indication of the duration of the
subsequent downlink TTI is received during the subsequent downlink
TTI; receive an indication of a duration of a subsequent uplink TTI
that follows the subsequent downlink TTI, wherein the indication of
the duration of the subsequent uplink TTI is received during the
subsequent downlink TTI; and communicate based at least in part on
the indication of the duration of the subsequent downlink TTI and
the indication of the duration of the subsequent uplink TTI.
28. The non-transitory computer-readable medium of claim 25,
wherein the indication of the duration of the uplink TTI indicates
that the duration of the uplink TTI is zero.
29. The non-transitory computer-readable medium of claim 25,
wherein the instructions are executable to: receive a set of
transport blocks (TBs) during the downlink TTI, wherein the
downlink TTI comprises a variable TTI; determine hybrid automatic
repeat request (HARQ) feedback for each TB of the set of TBs,
wherein a number of TBs in the set of TBs is based at least in part
on the duration of the downlink TTI; and transmit the HARQ feedback
for at least one TB of the set of TBs during the uplink TTI.
30. The non-transitory computer-readable medium of claim 25,
wherein the instructions are executable to: enter a low power state
during the downlink TTI or the uplink TTI based at least in part on
an absence of a grant of resources during the downlink TTI or the
uplink TTI.
Description
CROSS REFERENCES
[0001] The present application for patent claims priority to U.S.
Provisional Patent Application No. 62/068,416, entitled "Feedback
for Variable Transmission Time Intervals," filed Oct. 24, 2014, and
U.S. Provisional Patent Application No. 62/075,624, entitled
"Flexible Multiplexing Operation for Downlink Data," filed Nov. 5,
2014, assigned to the assignee hereof, and expressly incorporated
by reference herein.
BACKGROUND
[0002] 1. Field of Disclosure
[0003] The following relates generally to wireless communication,
and more specifically to flexible multiplexing operation for
downlink (DL) data and hybrid automatic repeat request (HARM)
feedback for variable transmission time interval (TTI), including
variable TTIs for enhanced component carriers (eCC).
[0004] 2. Description of Related Art
[0005] Wireless communications systems are widely deployed to
provide various types of communication content such as voice,
video, packet data, messaging, broadcast, and so on. These systems
may be multiple-access systems capable of supporting communication
with multiple users by sharing the available system resources
(e.g., time, frequency, and power). Examples of such
multiple-access systems include code division multiple access
(CDMA) systems, time division multiple access (TDMA) systems,
frequency division multiple access (FDMA) systems, and orthogonal
frequency division multiple access (OFDMA) systems, (e.g., a Long
Term Evolution (LTE) system).
[0006] By way of example, a wireless multiple-access communications
system may include a number of base stations, each simultaneously
supporting communication for multiple communication devices, which
may be otherwise known as user equipment (UEs). A base station may
communicate with the communication devices on downlink channels
(e.g., for transmissions from a base station to a UE) and uplink
channels (e.g., for transmissions from a UE to a base station).
[0007] Some wireless systems may employ time division duplexing
(TDD), in which the same frequency resources are used for UL and DL
transmissions. In such systems, a multiplexing mode may be selected
to serve multiple UEs. For example, a base station may choose to
switch to UL after transmitting data to a single UE, after
transmitting to multiple UEs one after the other, or after
transmitting to multiple UEs that are allocated different frequency
ranges. However, each method may result in a different tradeoffs
between latency, resource efficiency, and scheduling
flexibility.
[0008] Increasingly, many wireless applications benefit from
reduced latency communication. Additionally, wide bandwidth
carriers and spectrum sharing (e.g., unlicensed spectrum use) have
introduced more flexibility, and a greater number of variables for
efficient system operation, including issues related to efficient
feedback to maintain low latency.
SUMMARY
[0009] Methods, systems, and apparatuses for flexible multiplexing
operation for DL data are described. Within a TDD system, for
example, a multiplexing configuration may be selected or identified
based on latency and efficiency considerations. A base station may
implement the multiplexing configuration by transmitting a
combination of a resource grant, a signal indicating the length of
a downlink (DL) transmission time interval (TTI), and a signal
indicating the length of a subsequent uplink (UL) TTI to one or
more user equipment (UEs). If the latency and efficiency
considerations change, the base station may dynamically select a
new multiplexing configuration by, for example, setting the length
of an UL TTI to zero or assigning multiple UEs resources in the
same DL TTI.
[0010] Additionally, methods, systems, and apparatuses for
providing feedback for systems employing variable TTI are
described. Latency for downlink feedback may be reduced by
employing block feedback, including block hybrid automatic repeat
request (HARQ) feedback for an eCC. A UE, for example, may receive
a set of transport blocks (TBs) in a variable downlink TTI. The UE
may determine HARQ feedback for each TB of the set of TBs, and the
number of TBs in the set may be based on a time duration of the
variable downlink TTI. The UE may transmit, in an uplink TTI
following the downlink TTI, the HARQ feedback for each TB. In some
cases, HARQ feedback may be bundled for two or more TBs of the set
of TBs if, for instance, a maximum number of HARQ resources for the
uplink TTI would otherwise be exceeded.
[0011] Uplink feedback may also improve latency. For instance, a UE
may receive a grant for an uplink TB or for a retransmission of an
uplink TB. The UE may determine that the grant represents an
acknowledgment (ACK) when the grant is for an original transmission
TB, or the UE may determine that the grant represents a negative
acknowledgment (NACK) when the grant is for a retransmission of a
TB.
[0012] Additionally or alternatively, uplink transmissions may be
multiplexed in a way that improves latency. A base station, for
example, may receive a first set of HARQ feedback for each TB of a
first set of TBs, transmitted using a variable downlink TTI, from a
first UE during a first uplink TTI. The base station may also
concurrently receive a second set of HARQ feedback for each TB of a
second set of TBs from a second UE during the first uplink TTI.
[0013] A method of wireless communication is described. The method
may include identifying a downlink transmission time interval (TTI)
of a time-division duplex (TDD) configured carrier, receiving an
indication of a duration of the downlink TTI during the downlink
TTI and receiving an indication of a duration of an uplink TTI that
follows the downlink TTI. The indication of the uplink TTI duration
may be received during the downlink TTI. The method may also
include communicating based at least in part on the indication of
the downlink TTI and the indication of the uplink TTI.
[0014] An apparatus for wireless communication is described. The
apparatus may include means for identifying a downlink transmission
time interval (TTI) of a time-division duplex (TDD) configured
carrier, means for receiving an indication of a duration of the
downlink TTI during the downlink TTI, and means for receiving an
indication of a duration of an uplink TTI that follows the downlink
TTI. The indication of the uplink TTI duration may be received
during the downlink TTI and the means for communicating may be
operable based at least in part on the indication of the downlink
TTI and the indication of the uplink TTI.
[0015] A further apparatus is described. The apparatus may include
a processor, memory in electronic communication with the processor,
and instructions stored in the memory. The instructions may be
operable to cause the apparatus to identify a downlink transmission
time interval (TTI) of a time-division duplex (TDD) configured
carrier, receive an indication of a duration of the downlink TTI
during the downlink TTI, and receive an indication of a duration of
an uplink TTI that follows the downlink TTI. The indication of the
uplink TTI duration may be received during the downlink TTI. The
instructions may also be operable to cause the apparatus to
communicate based at least in part on the indication of the
downlink TTI and the indication of the uplink TTI.
[0016] A non-transitory computer readable medium for wireless
communication is described. The non-transitory computer-readable
medium may include instructions executable to identify a downlink
transmission time interval (TTI) of a time-division duplex (TDD)
configured carrier, receive an indication of a duration of the
downlink TTI during the downlink TTI, and receive an indication of
a duration of an uplink TTI that follows the downlink TTI. The
indication of the uplink TTI duration may be received during the
downlink TTI. The instructions may also be executable to
communicate based on the indication of the downlink TTI and the
indication of the uplink TTI.
[0017] Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving a
downlink grant during the downlink TTI, where the downlink grant
assigns a first set of resources during the downlink TTI.
[0018] Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving an
additional downlink grant that assigns a second set of resources
during the downlink TTI.
[0019] In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the first set of
resources and the second set of resources are frequency division
multiplexed (FDM) during the downlink TTI.
[0020] Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for receiving a
subsequent downlink grant during a subsequent downlink TTI that
follows the downlink TTI. Some examples of the method, apparatus,
or non-transitory computer-readable medium described above may
further include processes, features, means, or instructions for
receiving an indication of a duration of a subsequent downlink TTI
that follows the downlink TTI, wherein the indication of the
duration of the subsequent downlink TTI is received during the
subsequent downlink TTI. Some examples of the method, apparatus, or
non-transitory computer-readable medium described above may further
include processes, features, means, or instructions for receiving
an indication of a duration of a subsequent uplink TTI that follows
the subsequent downlink TTI, where the indication of the duration
of the subsequent uplink TTI is received during the subsequent
downlink TTI. Some examples of the method, apparatus, or
non-transitory computer-readable medium described above may further
include processes, features, means, or instructions for
communicating based on the indication of the duration of the
subsequent downlink TTI and the indication of the duration of the
subsequent uplink TTI.
[0021] In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the indication of the
duration of the uplink TTI indicates that the duration of the
uplink TTI is zero.
[0022] In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the downlink TTI duration
and a subsequent downlink TTI duration form a downlink burst that
is time division multiplexed on resources of the TDD configured
carrier.
[0023] In some examples of the method, apparatus, or non-transitory
computer-readable medium described above, the communicating
comprises: receiving a set of transport blocks (TBs) during the
downlink TTI, where the downlink TTI comprises a variable TTI. Some
examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for determining hybrid
automatic repeat request (HARQ) feedback for each TB of the set of
TBs, where a number of TBs in the set is based on the duration of
the downlink TTI. Some examples of the method, apparatus, or
non-transitory computer-readable medium described above may further
include processes, features, means, or instructions for
transmitting the HARQ feedback for at least one TB of the set of
TBs during the uplink TTI.
[0024] Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for determining HARQ
feedback for a number of code blocks (CBs), where each TB of the
set of TBs comprises at least one CB. In some cases, a quantity of
CBs in each TB may be based at least in part on a size of each TB.
Some examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for transmitting the
HARQ feedback for the number of CBs during the uplink TTI. Some
examples of the method, apparatus, or non-transitory
computer-readable medium described above may further include
processes, features, means, or instructions for entering a low
power state during the downlink TTI or the uplink TTI based at
least in part on an absence of a grant of resources during the
downlink TTI or the uplink TTI.
[0025] The foregoing has outlined rather broadly the features and
technical advantages of examples according to the disclosure in
order that the detailed description that follows may be better
understood. Additional features and advantages will be described
hereinafter. The conception and specific examples disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
disclosure. Such equivalent constructions do not depart from the
scope of the appended claims. Characteristics of the concepts
disclosed herein, both their organization and method of operation,
together with associated advantages will be better understood from
the following description when considered in connection with the
accompanying figures. Each of the figures is provided for the
purpose of illustration and description only, and not as a
definition of the limits of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] A further understanding of the nature and advantages of the
present disclosure may be realized by reference to the following
drawings. In the appended figures, similar components or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a dash and a second label that distinguishes among the similar
components. If just the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label.
[0027] FIG. 1 illustrates an example of a wireless communications
system for flexible multiplexing operation for downlink (DL) data
in accordance with various aspects of the present disclosure;
[0028] FIG. 2 illustrates an example of a wireless communications
system for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure;
[0029] FIG. 3A illustrates an example of a TDD UL/DL burst
configuration for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure;
[0030] FIG. 3B illustrates an example of a time division
multiplexing (TDM) UL/DL burst configuration for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0031] FIG. 3C illustrates an example of a frequency division
multiplexing (FDM) UL/DL burst configuration for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0032] FIG. 4 illustrates an example of a process flow for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0033] FIG. 5 shows a block diagram of a user equipment (UE)
configured for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure;
[0034] FIG. 6 shows a block diagram of a UE configured for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0035] FIG. 7 shows a block diagram of a flexible multiplexing
module configured for flexible multiplexing operation for DL data
in accordance with various aspects of the present disclosure;
[0036] FIG. 8 illustrates a block diagram of a system including a
UE configured for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure;
[0037] FIG. 9 shows a block diagram of a base station configured
for flexible multiplexing operation for DL data in accordance with
various aspects of the present disclosure;
[0038] FIG. 10 shows a block diagram of a base station flexible
multiplexing module configured for flexible multiplexing operation
for DL data in accordance with various aspects of the present
disclosure;
[0039] FIG. 11 shows a block diagram of a base station configured
for flexible multiplexing operation for DL data in accordance with
various aspects of the present disclosure;
[0040] FIG. 12 illustrates a block diagram of a system including a
base station configured for flexible multiplexing operation for DL
data in accordance with various aspects of the present
disclosure;
[0041] FIG. 13 is illustrates an example of radio frames and
different subframes that may be transmitted using different cells
of a wireless communication system in accordance with aspects of
the present disclosure;
[0042] FIG. 14 illustrates an example of enhanced component carrier
(eCC) transmissions in accordance with various aspects of the
present disclosure;
[0043] FIG. 15 illustrates an example of eCC transmissions in
accordance with various aspects of the present disclosure;
[0044] FIG. 16 illustrates an example of feedback for a carrier
employing variable transmission time intervals (TTI) in accordance
with various aspects of the present disclosure;
[0045] FIG. 17 illustrates a portion of a carrier with uplink
channel multiplexing for providing feedback for a variable TTI in
accordance with various aspects of the present disclosure;
[0046] FIG. 18 shows a block diagram of a user equipment (UE)
configured for feedback for variable TTI in accordance with various
aspects of the present disclosure;
[0047] FIG. 19 shows a block diagram of a UE configured for
feedback for variable TTI in accordance with various aspects of the
present disclosure;
[0048] FIG. 20 shows a block diagram of a feedback module
configured for feedback for variable TTI in accordance with various
aspects of the present disclosure;
[0049] FIG. 21 illustrates a block diagram of a system including a
UE configured for feedback for variable TTI in accordance with
various aspects of the present disclosure;
[0050] FIG. 22 shows a block diagram of a base station configured
for feedback for variable TTI in accordance with various aspects of
the present disclosure;
[0051] FIG. 23 shows a block diagram of a base station configured
for feedback for variable TTI in accordance with various aspects of
the present disclosure;
[0052] FIG. 24 shows a block diagram of a base station feedback
module configured for feedback for variable TTI in accordance with
various aspects of the present disclosure;
[0053] FIG. 25 illustrates a block diagram of a system including a
base station configured for feedback for variable TTI in accordance
with various aspects of the present disclosure;
[0054] FIG. 26 shows a flowchart illustrating a method for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0055] FIG. 27 shows a flowchart illustrating a method for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0056] FIG. 28 shows a flowchart illustrating a method for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0057] FIG. 29 shows a flowchart illustrating a method for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure;
[0058] FIG. 30 shows a flowchart illustrating a method for feedback
for variable TTI, in accordance with various aspects of the present
disclosure;
[0059] FIG. 31 shows a flowchart illustrating a method for feedback
for variable TTI in accordance with various aspects of the present
disclosure;
[0060] FIG. 32 shows a flowchart illustrating a method for feedback
for variable TTI in accordance with various aspects of the present
disclosure;
[0061] FIG. 33 shows a flowchart illustrating a method for feedback
for variable TTI in accordance with various aspects of the present
disclosure;
[0062] FIG. 34 shows a flowchart illustrating a method for feedback
for variable TTI in accordance with various aspects of the present
disclosure; and
[0063] FIG. 35 shows a flowchart illustrating a method for feedback
for variable TTI in accordance with various aspects of the present
disclosure.
DETAILED DESCRIPTION
[0064] A base station may multiplex downlink (DL) data for a user
equipment (UE) according to one of several multiplexing schemes:
time division duplex (TDD) multiplexing, time division multiplexing
(TDM), and frequency division multiplexing (FDM). Each multiplexing
scheme may offer certain benefits over other schemes with respect
to latency, efficiency, and scheduling flexibility.
[0065] According to the particular benefits of each multiplexing
scheme, one type of multiplexing may be more suitable for a certain
type of transmission than another. Thus, a physical layer signaling
mechanism may allow a base station to flexibly and dynamically
choose one of the multiplexing modes, depending, for example, on
the status of the base station. The mechanism may use two (2) layer
one (L1) signals (e.g., physical DL format indicator channel
(PDFICH) and physical UL format indicator channel (PUFICH)) to
indicate the length of a transmit time interval (TTI) and the
length of an UL burst. For example, PDFICH, which is present on the
first symbol, the last symbol, or another predetermined symbol
location of a DL TTI, may convey the DL TTI length, and PUFICH,
which is present on either the first of last symbol of a DL TTI,
may convey the burst length of an UL. The mechanism may be used in
conjunction with any of the three multiplexing schemes described
above.
[0066] For example, in the case of TDD multiplexing, a first PDFICH
on a first DL TTI may indicate the length of the first DL TTI and a
first PUFICH on the first DL TTI may indicate the length of a first
UL burst. Similarly, a second PDFICH on a second (e.g., subsequent)
DL TTI may indicate the length of the second DL TTI, while a second
PUFICH on the second DL TTI may indicate the length of a second UL
burst.
[0067] In the case of TDM, a first PDFICH on a first DL TTI may
indicate the length of the first DL TTI. If the first DL TTI is
immediately followed by a second DL TTI, the value (e.g., payload)
of the first PUFICH may be set to zero, thus signaling that the DL
transmission is to continue and that a UE may read the next symbol
(e.g., TTI) for the second PDFICH. The second PDFICH on the second
DL TTI may indicate the length of the second DL TTI. The second DL
TTI may include a second PUFICH which may indicate the length of a
subsequent UL burst.
[0068] In the case of FDM, a single PDFICH and PUFICH may be used
to signal a multiplexing format. For instance, a DL TTI may include
PDFICH which may indicate the length of the DL TTI. Due to the
frequency-division nature of FDM, an FDM DL TTI may be shared by
data assigned to two different UEs. Thus, a physical DL control
channel (PDCCH) may indicate the frequency regions assigned to each
UE. The DL TTI may also include PUFICH, which may be used to
indicate the length of an UL burst subsequent to the DL TTI.
[0069] Additionally or alternatively, techniques are described for
feedback, including hybrid automatic repeat request (HARQ)
feedback, for downlink variable length transmission time intervals
(TTI). A user equipment (UE) may receive a number of transport
blocks (TBs) in consecutive downlink TTIs. The UE may determine
HARQ feedback for each of the TBs, and it may transmit the feedback
for each TB in a subsequent uplink TTI. The UE may thus transmit a
block of feedback with acknowledgments (ACK) or negative ACK (NACK)
for each TB received during several downlink TTIs in a single
uplink TTI. In some examples, several UEs may concurrently transmit
feedback during a common uplink TTI. Communications between the UE
and a base station may thus decrease latency, as compared with a
fixed HARQ timeline, because the HARQ timing may be dynamically
adjusted to follow dynamically adjusted downlink bursts.
[0070] Additionally, in some examples, uplink HARQ feedback (e.g.,
feedback for uplink transmissions) may be entirely avoided. A UE
my, for example, determine whether an uplink transmission was
successfully received based on a subsequent grant. This may further
decrease latency because the base station may provide feedback
without the necessity of an additional ACK or NACK
transmission.
[0071] The following description provides examples, and is not
limiting of the scope, applicability, or examples set forth in the
claims. Changes may be made in the function and arrangement of
elements discussed without departing from the scope of the
disclosure. Various examples may omit, substitute, or add various
procedures or components as appropriate. For instance, the methods
described may be performed in an order different from that
described, and various steps may be added, omitted, or combined.
Also, features described with respect to some examples may be
combined in other examples.
[0072] FIG. 1 illustrates an example of a wireless communications
system 100 in accordance with various aspects of the present
disclosure. The system 100 includes base stations 105, UEs 115, and
a core network 130. The core network 130 may provide user
authentication, access authorization, tracking, internet protocol
(IP) connectivity, and other access, routing, or mobility
functions. The base stations 105 interface with the core network
130 through backhaul links 132 (e.g., S1, etc.). The base stations
105 may perform radio configuration and scheduling for
communication with the UEs 115, or may operate under the control of
a base station controller (not shown). In various examples, the
base stations 105 may communicate, either directly or indirectly
(e.g., through core network 130), with one another over backhaul
links 134 (e.g., X1, etc.), which may be wired or wireless
communication links.
[0073] The base stations 105 may wirelessly communicate with the
UEs 115 via one or more base station antennas. Each of the base
stations 105 may provide communication coverage for a respective
geographic coverage area 110. In some examples, base stations 105
may be referred to as a base transceiver station, a radio base
station, an access point, a radio transceiver, a NodeB, eNodeB
(eNB), Home NodeB, a Home eNodeB, or some other suitable
terminology. The geographic coverage area 110 for a base station
105 may be divided into sectors making up only a portion of the
coverage area (not shown). The wireless communications system 100
may include base stations 105 of different types (e.g., macro or
small cell base stations). There may be overlapping geographic
coverage areas 110 for different technologies. Each base station
105 may multiplex DL data for UEs according to one of several
multiplexing schemes, which may be selected based on the particular
latency requirements of each UE.
[0074] In some examples, at least a portion of the wireless
communications system 100 may be configured to operate using
variable length (i.e., variable) TTIs, in which downlink and uplink
TTIs may be dynamically adjusted to provide flexibility to
dynamically adapt to particular traffic needs at a particular
moment. UEs 115 may determine feedback for TBs received during
variable downlink TTIs, and the UEs 115 may transmit the determined
feedback during a subsequent TTI. The feedback transmission may be
scheduled by a grant received during a downlink TTI, or the
feedback may be sent in a first uplink TTI following a downlink
TTI, irrespective of a grant. Feedback from several UEs 115 may be
multiplexed in a common uplink TTI and received by a base station
105. Additionally or alternatively, a base station 105 may
indicated feedback to a UE 115 with a grant, and without the
necessity of an ACK or NACK transmission.
[0075] In some examples, the wireless communications system 100 is
a Long Term Evolution (LTE)/LTE-Advanced (LTE-A) network. In
LTE/LTE-A networks, the term evolved node B (eNB) may be generally
used to describe the base stations 105. The wireless communications
system 100 may be a heterogeneous LTE/LTE-A network in which
different types of eNBs provide coverage for various geographical
regions. For example, each eNB or base station 105 may provide
communication coverage for a macro cell, a small cell, or other
types of cell. The term "cell" is a 3GPP term that can be used to
describe a base station, a carrier or component carrier associated
with a base station, or a coverage area (e.g., sector, etc.) of a
carrier or base station, depending on context.
[0076] A macro cell generally covers a relatively large geographic
area (e.g., several kilometers in radius) and may allow
unrestricted access by UEs 115 with service subscriptions with the
network provider. A small cell is a lower-powered base station, as
compared with a macro cell, that may operate in the same or
different (e.g., licensed, unlicensed, etc.) frequency bands as
macro cells. Small cells may include pico cells, femto cells, and
micro cells according to various examples. A pico cell, for
example, may cover a small geographic area and may allow
unrestricted access by UEs 115 with service subscriptions with the
network provider. A femto cell may also cover a small geographic
area (e.g., a home) and may provide restricted access by UEs 115
having an association with the femto cell (e.g., UEs 115 in a
closed subscriber group (CSG), UEs 115 for users in the home, and
the like). An eNB for a macro cell may be referred to as a macro
eNB. An eNB for a small cell may be referred to as a small cell
eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one
or multiple (e.g., two, three, four, and the like) cells (e.g.,
component carriers).
[0077] The wireless communications system 100 may support
synchronous or asynchronous operation. For synchronous operation,
the base stations 105 may have similar frame timing, and
transmissions from different base stations 105 may be approximately
aligned in time. For asynchronous operation, the base stations 105
may have different frame timing, and transmissions from different
base stations 105 may not be aligned in time. The techniques
described herein may be used for either synchronous or asynchronous
operations.
[0078] The communication networks that may accommodate some of the
various disclosed examples may be packet-based networks that
operate according to a layered protocol stack. In the user plane,
communications at the bearer or packet data convergence protocol
(PDCP) layer may be IP-based. A radio link control (RLC) layer may
perform packet segmentation and reassembly to communicate over
logical channels. A medium access control (MAC) layer may perform
priority handling and multiplexing of logical channels into
transport channels. The MAC layer may also use HARQ to provide
retransmission at the MAC layer to improve link efficiency. In the
control plane, the radio resource control (RRC) protocol layer may
provide establishment, configuration, and maintenance of an RRC
connection between a UE 115 and the base stations 105. The RRC
protocol layer may also be used for core network 130 support of
radio bearers for the user plane data. At the physical (PHY) layer,
the transport channels may be mapped to physical channels.
[0079] The UEs 115 may be dispersed throughout the wireless
communications system 100, and each UE 115 may be stationary or
mobile. A UE 115 may also include or be referred to by those
skilled in the art as a mobile station, a subscriber station, a
mobile unit, a subscriber unit, a wireless unit, a remote unit, a
mobile device, a wireless device, a wireless communications device,
a remote device, a mobile subscriber station, an access terminal, a
mobile terminal, a wireless terminal, a remote terminal, a handset,
a user agent, a mobile client, a client, or some other suitable
terminology. A UE 115 may be a cellular phone, a personal digital
assistant (PDA), a wireless modem, a wireless communication device,
a handheld device, a tablet computer, a laptop computer, a cordless
phone, a wireless local loop (WLL) station, or the like. A UE may
be able to communicate with various types of base stations and
network equipment including macro eNBs, small cell eNBs, relay base
stations, and the like.
[0080] The communication links 125 shown in wireless communications
system 100 may include uplink (UL) transmissions from a UE 115 to a
base station 105, or DL transmissions, from a base station 105 to a
UE 115. The DL transmissions may also be called forward link
transmissions while the UL transmissions may also be called reverse
link transmissions. Each communication link 125 may include one or
more carriers, where each carrier may be a signal made up of
multiple sub-carriers (e.g., waveform signals of different
frequencies) modulated according to the various radio technologies
described above. Each modulated signal may be sent on a different
sub-carrier and may carry control information (e.g., reference
signals, control channels, etc.), overhead information, user data,
etc.
[0081] The communication links 125 may transmit bidirectional
communications using frequency division duplex (FDD) (e.g., using
paired spectrum resources) or TDD operation (e.g., using unpaired
spectrum resources). Frame structures may be defined for FDD (e.g.,
frame structure type 1) and TDD (e.g., frame structure type 2). A
UE 115 may, for example, identify a TDD configuration of carrier,
and the UE 115 may receive different multiplexing format signals
indicative of different multiplexing configurations of various TTIs
of the TDD carrier.
[0082] In some examples of the system 100, base stations 105 or UEs
115 may include multiple antennas for employing antenna diversity
schemes to improve communication quality and reliability between
base stations 105 and UEs 115. Additionally or alternatively, base
stations 105 or UEs 115 may employ multiple input multiple output
(MIMO) techniques that may take advantage of multi-path
environments to transmit multiple spatial layers carrying the same
or different coded data.
[0083] Wireless communications system 100 may support operation on
multiple cells or carriers, a feature which may be referred to as
carrier aggregation (CA) or multi-carrier operation. A carrier may
also be referred to as a component carrier (CC), a layer, a
channel, etc. The terms "carrier," "component carrier," "cell," and
"channel" may be used interchangeably herein. A UE 115 may be
configured with multiple DL CCs and one or more UL CCs for carrier
aggregation. Carrier aggregation may be used with both FDD and TDD
component carriers. The terms "carrier" and "cell" may be used in
the context of carrier aggregation, and they may also refer to a
wireless communications system 100 with a single carrier (or a
single set of paired UL/DL carriers). For example, the term
"serving cell" may refer to either a primary cell or secondary cell
in a carrier aggregation context, or to the single cell serving a
UE 115 in a non-carrier aggregation context.
[0084] Carriers may transmit bidirectional communications using FDD
(e.g., using paired spectrum resources) or TDD operation (e.g.,
using unpaired spectrum resources). Different carriers, or cells,
may be configured with different frame structures (e.g., FDD or
TDD), and each TTI of the carrier may utilize one of several
different multiplexing configurations. For TDD frame structures,
each subframe may carry UL or DL traffic, and special subframes may
be used to switch between DL and UL transmission. Allocation of UL
and DL subframes within radio frames may be symmetric or asymmetric
and may be statically determined or may be reconfigured
semi-statically. Special subframes may carry DL or UL traffic and
may include a Guard Period (GP) between DL and UL traffic.
Switching from UL to DL traffic may be achieved by setting a timing
advance at the UE 115 without the use of special subframes or a
guard period. UL-DL configurations with switch-point periodicity
equal to the frame period (e.g., 10 ms) or half of the frame period
(e.g., 5 ms) may also be supported.
[0085] For example, TDD frames may include one or more special
frames, and the period between special frames may determine the TDD
DL-to-UL switch-point periodicity for the frame. Use of TDD offers
flexible deployments without requiring paired UL-DL spectrum
resources. In some TDD network deployments, interference may be
caused between UL and DL communications (e.g., interference between
UL and DL communication from different base stations, interference
between UL and DL communications from base stations and UEs, etc.).
For example, where different base stations 105 serve different UEs
115 within overlapping coverage areas according to different TDD
UL-DL configurations, a UE 115 attempting to receive and decode a
DL transmission from a serving base station 105 can experience
interference from UL transmissions from other, proximately located
UEs 115.
[0086] Time intervals in LTE and similar systems may be expressed
in multiples of a basic time unit (e.g., the sampling period,
T.sub.s=1/30,720,000 seconds). Time resources may be organized
according to radio frames of length of 10 ms
(T.sub.f=307200T.sub.s), which may be identified by a system frame
number (SFN) ranging from 0 to 1023. Each frame may include ten 1
ms subframes numbered from 0 to 9. A subframe may be further
divided into two 0.5 ms slots, each of which contains 6 or 7
modulation symbol periods (depending on the length of the cyclic
prefix prepended to each symbol). Excluding the cyclic prefix, each
symbol contains 2048 sample periods. In some cases the subframe may
be the smallest scheduling unit, also known as a TTI. In other
cases, a TTI may be shorter than a subframe or may be dynamically
selected (e.g., in short TTI bursts or in selected component
carriers using short TTIs).
[0087] Data in wireless communications system 100 may be divided
into logical channels, transport channels, and physical layer
channels. Channels may also be classified into Control Channels and
Traffic Channels. Logical control channels may include paging
control channel (PCCH) for paging information, broadcast control
channel (BCCH) for broadcast system control information, multicast
control channel (MCCH) for transmitting multimedia broadcast
multicast service (MBMS) scheduling and control information,
dedicated control channel (DCCH) for transmitting dedicated control
information, common control channel (CCCH) for random access
information, dedicated traffic channel (DTCH) for dedicated UE
data, and multicast traffic channel (MTCH), for multicast data. DL
transport channels may include broadcast channel (BCH) for
broadcast information, a DL shared channel (DL-SCH) for data
transfer, paging channel (PCH) for paging information, and
multicast channel (MCH) for multicast transmissions.
[0088] UL transport channels may include random access channel
(RACH) for access and UL shared channel (UL-SCH) for data. DL
physical channels may include physical broadcast channel (PBCH) for
broadcast information, physical control format indicator channel
(PCFICH) for control format information, physical DL control
channel (PDCCH) for control and scheduling information, physical
HARQ indicator channel (PHICH) for HARQ status messages, physical
DL shared channel (PDSCH) for user data and physical multicast
channel (PMCH) for multicast data. UL physical channels may include
physical random access channel (PRACH) for access messages,
physical UL control channel (PUCCH) for control data, and physical
UL shared channel (PUSCH) for user data.
[0089] According the present disclosure, additional channels may be
used to indicate the length of DL and UL TTIs to achieve different
multiplexing configurations. For example, a physical DL format
indicator channel (PDFICH) may indicate the length of a DL TTI and
a physical UL format indicator channel (PUFICH) may indicate the
length of an UL TTI. PDFICH and PUFICH may be used in conjunction
with a resource grant (e.g., in PDCCH) to configure a selected
multiplexing format.
[0090] PDCCH may carry DL control information (DCI) in control
channel elements (CCEs), which may consist of nine logically
contiguous resource element groups (REGs), where each REG contains
4 resource elements (REs). DCI includes information regarding DL
scheduling assignments, UL resource grants, transmission scheme, UL
power control, HARQ information, modulation and coding scheme (MCS)
and other information.
[0091] PDCCH can carry DCI messages associated with multiple users,
and each UE 115 may decode the DCI messages that are intended for
it. For example, each UE 115 may be assigned a cell radio network
temporary identifier (C-RNTI) and cyclic redundancy check (CRC)
bits attached to each DCI may be scrambled based on the C-RNTI. To
reduce power consumption and overhead at the user equipment, a
limited set of CCE locations can be specified for DCI associated
with a specific UE 115. CCEs may be grouped (e.g., in groups of 1,
2, 4 and 8 CCEs), and a set of CCE locations in which the user
equipment may find relevant DCI may be specified. These CCEs may be
known as a search space.
[0092] The search space can be partitioned into two regions: a
common CCE region or search space and a UE-specific (dedicated) CCE
region or search space. The common CCE region may be monitored by
all UEs served by a base station 105 and may include information
such as paging information, system information, random access
procedures, multiplexing format information, and the like. The
UE-specific search space may include user-specific control
information. A UE 115 may attempt to decode DCI by performing a
process known as a blind decode, during which search spaces are
randomly decoded until the DCI is detected. During a blind decode,
the user equipment may attempt descramble all potential DCI
messages using its C-RNTI, and perform a CRC check to determine
whether the attempt was successful.
[0093] According to the present disclosure, a base station 105 in a
TDD system, for instance, may identify a multiplexing configuration
based on latency and efficiency considerations of UEs 115 within
the system 100. The base station 105 may then implement the
multiplexing configuration by transmitting a combination of one or
more PDCCH messages, a PDFICH indicating the length of a DL TTI,
and a PUFICH indicating the length of a subsequent UL TTI to one or
more UEs 115. If the latency and efficiency considerations change,
the base station 105 may dynamically select a new multiplexing
configuration by, for example, setting the length of an UL TTI to
zero using PUFICH or assigning multiple UEs 115 resources in the
same DL TTI via PDCCH.
[0094] The term "component carrier" may refer to each of the
multiple carriers utilized by a UE in carrier aggregation (CA)
operation, and may be distinct from other portions of system
bandwidth. For instance, a component carrier may be a relatively
narrow-bandwidth carrier susceptible of being utilized
independently or in combination with other component carriers. Each
component carrier may provide the same capabilities as an isolated
carrier based on release 8 or release 9 of the LTE standard.
Multiple component carriers may be aggregated or utilized
concurrently to provide some UEs 115 with greater bandwidth and,
e.g., higher data rates. Thus, individual component carriers may be
backwards compatible with legacy UEs 115 (e.g., UEs 115
implementing LTE release 8 or release 9); while other UEs 115
(e.g., UEs 115 implementing post-release 8/9 LTE versions), may be
configured with multiple component carriers in a multi-carrier
mode.
[0095] A carrier used for DL may be referred to as a DL CC, and a
carrier used for UL may be referred to as an UL CC. A UE 115 may be
configured with multiple DL CCs and one or more UL CCs for carrier
aggregation. Each carrier may be used to transmit control
information (e.g., reference signals, control channels, etc.),
overhead information, data, etc. A UE 115 may communicate with a
single base station 105 utilizing multiple carriers, and may also
communicate with multiple base stations simultaneously on different
carriers. Each cell of a base station 105 may include an UL
component carrier (CC) and a DL CC. The coverage area 110 of each
serving cell for a base station 105 may be different (e.g., CCs on
different frequency bands may experience different path loss).
[0096] In some examples, one carrier is designated as the primary
carrier, or primary component carrier (PCC), for a UE 115, which
may be served by a primary cell (PCell). Primary cells may be
semi-statically configured by higher layers (e.g., radio resource
control (RRC), etc.) on a per-UE basis. Certain uplink control
information (UCI), and scheduling information transmitted on
physical uplink control channel (PUCCH), are carried by the primary
cell. Additional carriers may be designated as secondary carriers,
or secondary component carriers (SCC), which may be served by
secondary cells (SCells). Secondary cells may likewise be
semi-statically configured on a per-UE basis. In some cases,
secondary cells may not include or be configured to transmit the
same control information as the primary cell. In some examples, and
as described below, an enhanced component carrier (eCC) may be
configured--e.g., as an SCell. An eCC may utilize variable TTIs,
which may be dynamically adjusted according to traffic
conditions.
[0097] In some cases, a UE 115 may be served by cells from two or
more base stations 105 that are connected by a non-ideal backhaul
link 134 in dual connectivity operation. For example, the
connection between the serving base stations 105 may not be
sufficient to facilitate precise timing coordination. Thus, in some
cases, the cells serving a UE 115 may be divided into multiple
timing adjustment group (TAGs). Each TAG may be associated with a
different timing offset, such that the UE 115 may synchronize UL
transmissions differently for different UL carriers.
[0098] In some examples, one cell may utilize licensed spectrum,
while another cell may utilize unlicensed spectrum. An eCC may be
configured for unlicensed spectrum, for instance. Broadly speaking,
the unlicensed spectrum in some jurisdictions may range from 600
Megahertz (MHz) to 6 Gigahertz (GHz). As used herein, the term
"unlicensed spectrum" or "shared spectrum" may thus refer to
industrial, scientific and medical (ISM) radio bands, irrespective
of the frequency of those bands. In some examples, unlicensed
spectrum is the U-NII radio band, which may also be referred to as
the 5 GHz or 5G band. By contrast, the term "licensed spectrum" or
"cellular spectrum" may be used herein to refer to wireless
spectrum utilized by wireless network operators under
administrative license from a governing agency.
[0099] FIG. 2 illustrates an example of a wireless communications
system 200 for flexible multiplexing operation for DL data in TDD
systems in accordance with various aspects of the present
disclosure. Wireless communications system 200 may include UE
115-a, which may be an example of a UE 115 described above with
reference to FIG. 1. Wireless communications system 200 may also
include a base station 105-a, which may be an example of a base
station 105 described above with reference to FIG. 1. Base station
105-a may communicate with any UE 115 within its coverage area
110-a (e.g., via downlink 205 and uplink 210, which may utilize the
same frequency range), as generally described above with respect to
FIG. 1.
[0100] Wireless communications system 200 may use TDD for both
uplink 210 and downlink 205 (e.g., frequency resources may be
allocated between uplink 210 and downlink 205 in a time-division
manner). For example, base station 105-a may send data on downlink
205 during a TTI 215 in which UE 115-a is not allocated UL
frequency resources. Similarly, UE 115-a may transmit data on
uplink 210 during TTI 220 in which base station 105-a has not
allocated any frequency resources for DL transmissions. Base
station 105-a may flexibly and dynamically choose multiplexing
modes for individual TTIs on downlink 205, according to the type of
traffic, and signal the chosen multiplexing mode to UE 115-a via
control channels.
[0101] For instance, base station 105-a may determine a
multiplexing configuration (e.g., frequency division multiplexing)
for TTI 215 within DL burst 225. Additionally, base station 105-a
may signal the multiplexing format of TTI 215 (e.g., the length of
TTI) to UE 115-a via a multiplexing format signal on a DL control
channel (e.g., via PDFICH) which may be conveyed during TTI 215. In
some cases, base station 105-a may signal the length of an uplink
(UL) period subsequent to TTI 215 via a multiplexing format signal
on an UL control channel (e.g., PUFICH). Thus, base station 105-a
may convey multiplexing configuration information to UE 115-a via a
DL control channel and an UL control channel.
[0102] Base station 105-a may identify a multiplexing configuration
based on latency and efficiency considerations. Base station 105-a
may then implement the multiplexing configuration by transmitting a
combination of one or more PDCCH messages, a PDFICH indicating the
length of a DL TTI, and a PUFICH indicating the length of a
subsequent UL TTI to UE 115-a. If the latency and efficiency
considerations change, base station 105-a may dynamically select a
new multiplexing configuration by, for example, setting the length
of an UL TTI to zero using PUFICH or assigning multiple UEs 115
resources in the same DL TTI via PDCCH.
[0103] FIG. 3A illustrates an example of a TDD UL/DL burst
configuration 301 for flexible multiplexing operation for DL data
in TDD systems in accordance with various aspects of the present
disclosure. TDD UL/DL burst configuration 301 may illustrate
aspects of a multiplexing format used in conjunction with a TDD
system as described above with reference to FIGS. 1-2.
[0104] DL burst 305-a may represent allocated resources for a
single TTI 310-a directed to an individual UE 115. DL burst 305-a
may include one or more control channels such as PDCCH 315-a, which
may indicate data resource assignments (e.g., DL grant) to a first
UE 115 (FIGS. 1 and 2), and PDSCH 320-a, which may convey data
assigned to the first UE 115. Additionally, DL burst 305-a may
include PDFICH 325-a, and PUFICH 330-a. In some examples, PDFICH
325-a may indicate the length of TTI 310-a to a UE 115 and PUFICH
330-a may indicate the length of UL burst 335-a. Upon reception of
PUFICH 330-a, the UE 115 may switch a radio from a DL configuration
to an UL configuration and transmit an UL message on during UL
burst 335-a. Subsequently, based on the length of UL burst 335-a
indicated in PUFICH 330-a, the UE 115 may switch the radio from an
UL configuration to a DL configuration and to receive DL burst
305-b. DL burst 305-b may represent allocated resources for TTI
310-b and may include PDCCH 315-b, which may indicate data resource
assignments to a second UE 115, and PDSCH 320-b, which may convey
data for the second UE 115. Additionally, DL burst 305-b may
include PDFICH 325-b and PUFICH 330-b, which may indicate the
length of DL TTI 310-b and the length of UL burst 335-b,
respectively. The first and the second UE may be the same UE or
different UEs.
[0105] Thus, in a TDD multiplexing scheme, a base station may serve
a single UE at each DL burst. While a TDD scheme may enjoy low
latency delivery with immediate ACK/NACK, as well as scheduler
flexibility similar to TDM, the efficiency of a TDD scheme may, in
some cases, suffer due to frequent DL and uplink (UL)
switching.
[0106] FIG. 3B illustrates an example of TDM UL/DL burst
configuration 302 for flexible multiplexing operation for DL data
in TDD systems in accordance with various aspects of the present
disclosure. TDM UL/DL burst configuration 302 may illustrate
aspects of a multiplexing format used in conjunction with a TDD
system as described above with reference to FIGS. 1-2.
[0107] DL burst 305-c may represent allocated resources for two
TTIs, TTI 310-c and TTI 310-d. During TTI 310-c, PDCCH 315-c may
indicate data resource assignments for a first UE 115 and convey
data for a first UE 115 (e.g., on PDSCH 320-c). Additionally, TTI
310-c may include PDFICH 325-c which may indicate the length of TTI
310-c. To signal that TTI 310-c is contiguous to TTI 310-d, PUFICH
330-c may indicate an UL TTI length of zero. In other words, PUFICH
330-c may indicate to a UE 115 that it may immediately proceed to
read TTI 310-d and receive PDFICH 325-d. PDFICH 325-d may indicate
the length of DL TTI 310-d, and PUFICH 330-d may indicate the
length of UL burst 335-c. DL TTI 310-d may also include PDCCH 315-d
and PDSCH 320-d, which may include a data resource assignment and
data for the second UE 115, respectively. The first and the second
UE may be the same UE or different UEs.
[0108] Thus, a TDM scheme may enable a base station to serve
multiple UEs at each DL burst in a time-division manner.
Additionally, a TDM scheme may provide for low latency in data
delivery, as well as scheduler flexibility (e.g., a base station
may start transmitting a first data irrespective of the
availability of a second data). However, in a TDM scheme an
ACK/NACK for a first data may be delayed until a second data is
finished. Thus, a TDM scheme may, in some instances, incur some
ACK/NACK delay which may increase latency.
[0109] FIG. 3C illustrates an example of FDM UL/DL burst
configuration 303 for flexible multiplexing operation for DL data
in TDD systems in accordance with various aspects of the present
disclosure. FDM UL/DL burst configuration 303 may illustrate
aspects of a multiplexing format used in conjunction with a TDD
system as described above with reference to FIGS. 1 and 2.
[0110] DL burst 305-d may represent allocated resources for TTI
310-e, and may be configured to convey data for two UEs 115. For
instance, data for a first UE 115 may be conveyed by PDSCH 320-e
using frequency region 340 and data for a second UE 115 may be
conveyed by PDSCH 320-e using frequency region 345. To indicate
which data resources (e.g., frequency regions) are assigned to the
first UE 115 and the second UE 115, TTI 310-e may include PDCCH
315-e and PDCCH 315-f, respectively. TTI 310-e may also include
PDFICH 325-e, which may indicate the length of DL TTI 310-e, and
PUFICH 330-e, which may indicate the length of UL burst 335-d.
[0111] Thus, an FDM scheme may allow a base station to serve
multiple UEs at each DL burst in a frequency-division manner, but
may experience large latency (e.g., a first data may finish at the
same time as a second data). However, FDM may, in some instances,
be more efficient than TDD and TDM for several reasons, including
lower RS overhead, ease of frequency selective scheduling, and
closed-loop spatial multiplexing.
[0112] FIG. 4 illustrates an example of a process flow 400 for
flexible multiplexing operation for DL data in accordance with
various aspects of the present disclosure. While much of the
discussion of process flow 400 is in the context of a TDD system,
those skilled in the art will recognize the applicability of the
described techniques to other systems, including FDD systems.
Process flow 400 may include UE 115-b and UE 115-c, which may be
examples of UEs 115 described above with reference to FIG. 1.
Process flow 400 may also include a base station 105-b, which may
be an example of a base station 105 described above with reference
to FIG. 1. Additionally, process flow 400 may be an example of a
bi-directional communication scheme between any base station 105
and UE 115, such as described with reference to FIGS. 1-3C.
[0113] At step 405, base station 105-b may identify one or more
parameters that may be used to determine an appropriate
multiplexing configuration. For example, base station 105-b may
identify a target latency for an upcoming data transmission to UE
115-b. The latency target identification may be based on a traffic
type, an amount of data for transmission, a number of UEs 115
supported by base station 105-b, or on other factors.
Alternatively, base station 105-b may identify a different target
parameter based on efficiency or scheduling flexibility
considerations. Base station 105-b may then select a multiplexing
scheme (e.g., basic TDD, TDM, or FDM) based on the identified
parameters. In some examples, base station 105-b may select a
multiplexing scheme based on a combination of target parameters.
Base station 105-b may then multiplex a DL TTI using the chosen
multiplexing scheme. In some cases, UE 115-b and base station 105-b
may identify the communication link as a TDD communication link,
and the multiplexing scheme may be based on the underlying TDD
structure.
[0114] At step 410, base station 105-b may transmit (and UEs 115-b
and 115-c may receive) a downlink grant and a multiplexing format
signal on (e.g., via PDCCH and PDFICH). In some examples, PDFICH
may be a broadcast signal and may convey the length of the
corresponding DL TTI. In other examples, a channel other than
PDFICH may be used to convey the same information. Thus, UE 115-a
may receive a first multiplexing format signal (e.g., PDFICH) from
a serving cell of the carrier, the first multiplexing format signal
indicating a first multiplexing configuration of a first TTI.
[0115] At step 415, base station 105-b may transmit DL data for UE
115-b or 115-c to receive. The DL data may be conveyed on PDSCH,
for example, and may be decoded by UE 115-b or 115-c using resource
assignment information conveyed on the control channel (e.g.,
PDCCH). Thus, UE 115-a may receive a first data transmission from
the serving cell based on the first multiplexing configuration
during the first TTI. In some cases, UE 115-a may receive data
using a portion of the frequency tones of the TDD carrier and UE
115-c may receive data using another portion of the frequency tones
of the carrier (e.g., if base station 105-b selected an FDM
configuration and sends a DL grant to both UEs 115).
[0116] At step 420, base station 105-b may transmit (and UEs 115-b
and 115-c may receive) a subsequent multiplexing format signal on
an UL control channel (e.g., PUFICH). PUFICH may be a broadcast
signal and may indicate the length of a subsequent UL burst. Thus,
UE 115-b may receive a second multiplexing format signal from the
serving cell indicating a second multiplexing configuration of a
second TTI (e.g., the UL TTI), the second multiplexing
configuration may be different from the first multiplexing
configuration. In some examples, the PUFICH may be referred to as a
third multiplexing format signal, such as when the first TTI and
the second TTI represent DL TTIs and the third TTI is an UL TTI
between the first TTI and the second TTI. That is, a subsequent
PDFICH may be referred to as the second multiplexing format
signal.
[0117] In some cases the PUFICH may indicate the absence of an UL
TTI. For example, the PUFICH may indicate an UL TTI of size zero
(e.g., if base station 105-b selected a TDM configuration). Then UE
115-b may not switch the radio configuration. Rather, UE 115-b may
immediately receive the next DL transmissions (e.g., PDFICH, PDCCH,
or PDSCH).
[0118] At step 425, UE 115-b may switch a radio from a DL
configuration to an UL configuration based on PUFICH (e.g., during
a special subframe switching period). At step 430, UE 115-b may
transmit UL data to base station 105-b during the indicated length
of the UL burst. Subsequently, at step 435, UE 115-b may switch the
radio from an UL configuration to a DL configuration. In some
examples, the switch may be based on PUFICH.
[0119] In examples when UE 115-c does not receive any UL grant
during the first TTI, UE 115-c may enter a the low power mode
during the period indicated by PUFICH. During this period, UE 115-c
may remain in the DL configuration without switching its radio to
UL and then back to DL (i.e., because UE 115-c may not transmit
anything).
[0120] At step 440, base station 105-b may select a different
multiplexing configuration as described above with reference to
FIGS. 3A, 3B, and 3C. At step 445, base station 105-b may transmit
one or more DL grants and a multiplexing format signal according to
the updated multiplexing configuration. For example, in the case
when the first PUFICH is referred to as the third multiplexing
format signal, the second multiplexing format signal may be a
second PDFICH for the second DL burst.
[0121] When base station 105-b selects a TDD or TDM configuration,
the second DL TTI may be directed toward a different UE 115 as
described above with reference to FIGS. 3A and 3B. At step 450, or
during any DL or UL TTIs where the resources are allocated to
different UEs 115 (i.e., when no PDCCH is directed toward UE
115-b), UE 115-b may enter a low power state for a time period
based on the multiplexing format signals (e.g., PDFICH for a DL TTI
or PUFICH for an UL TTI). At step 455, UE 115-c may receive DL data
based on receiving a DL grant via PDCCH at step 445.
[0122] At step 460, UEs 115-b and 115-c may receive a fourth
multiplexing format signal (i.e., the second PUFICH) indicating a
length of a fourth TTI, wherein the fourth TTI is an UL TTI
following the second TTI.
[0123] FIG. 5 shows a block diagram 500 of a UE 115-d configured
for flexible multiplexing operation for DL data in accordance with
various aspects of the present disclosure. UE 115-d may be an
example of aspects of a UE 115 described with reference to FIGS.
1-4. UE 115-d may include a receiver 505, a flexible multiplexing
module 510, or a transmitter 515. UE 115-d may also include a
processor. Each of these components may be in communication with
one another.
[0124] The receiver 505 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to flexible multiplexing operation for DL data
in TDD systems, etc.). Information may be passed on to the flexible
multiplexing module 510, and to other components of UE 115-d. In
some examples, the receiver 505 may receive a first multiplexing
format signal and a first data transmission from the serving cell
based on the first multiplexing configuration during the first TTI.
The receiver 505 may, in some examples, receive a second
multiplexing format signal from the serving cell based at least in
part on the first TTI length and the third TTI length.
[0125] Additionally or alternatively, the receiver 505 may receive
a second data transmission from the serving cell based on the
second multiplexing configuration and the second DL grant. The
receiver 505 may receive an indication of a duration of a downlink
TTI, such as during the downlink TTI. The receiver 505 may receive
an indication of a duration of an uplink TTI that follows the
downlink TTI. The indication of the uplink TTI duration may be
received during the downlink TTI. The receiver 505 may also
represent examples of aspects of a transceiver 835 described with
reference to FIG. 8.
[0126] The flexible multiplexing module 510 may identify a TDD
configuration of a carrier, receive a first multiplexing format
signal from a serving cell of the carrier, the first multiplexing
format signal indicating a first multiplexing configuration of a
first TTI. In some cases, the flexible multiplexing module 510 may
identify a downlink TTI of a TDD configured carrier, receive an
indication of a duration of the downlink TTI, such as during the
downlink TTI, receive an indication of a duration of an uplink TTI
that follows the downlink TTI, and communicate based at least in
part on the indication of the downlink TTI and the indication of
the uplink TTI. The indication of the uplink TTI duration may be
received during the downlink TTI. It may also, in conjunction with
the receiver 505, receive a first data transmission from the
serving cell based on the first multiplexing configuration during
the first TTI, and it may receive a second multiplexing format
signal from the serving cell indicating a second multiplexing
configuration of a second TTI, the second multiplexing
configuration different from the first multiplexing configuration.
The flexible multiplexing module 510 may be an aspect of a
processor, such as the processor 805 described with reference to
FIG. 8.
[0127] The transmitter 515 may transmit signals received from other
components of UE 115-d. In some embodiments, the transmitter 515
may be collocated with the receiver 505 in a transceiver module.
The transmitter 515 may include a single antenna, or it may include
a plurality of antennas. In some examples, the transmitter 515 may
transmit a message to the serving cell during the third TTI. In
some examples, the transmitter 515 may transmit a message to the
serving cell during the fourth TTI. The transmitter 515 may also
transmit a first data transmission on the TDD carrier to a first UE
during the first TTI based on the first multiplexing configuration.
The transmitter 515 may illustrate aspects of a transceiver 835
described with reference to FIG. 8.
[0128] FIG. 6 shows a block diagram 600 of a UE 115-e for flexible
multiplexing operation for DL data in accordance with various
aspects of the present disclosure. UE 115-e may be an example of
aspects of a UE 115 described with reference to FIGS. 1-5. UE 115-e
may include a receiver 505-a, a flexible multiplexing module 510-a,
or a transmitter 515-a. UE 115-e may also include a processor. The
flexible multiplexing module 510-a may illustrate aspects of a
processor, such as the processor 805 described with reference to
FIG. 8. Each of these components may be in communication with one
another. The flexible multiplexing module 510-a may also include a
TDD module 605 and a PDFICH/PUFICH module 620. Each of these
components may illustrate aspects of a processor, such as the
processor 805 described with reference to FIG. 8.
[0129] The receiver 505-a may receive information which may be
passed on to flexible multiplexing module 510-a, and to other
components of UE 115-e. The receiver 505-a may illustrate aspects
of a transceiver 835 described with reference to FIG. 8. The
flexible multiplexing module 510-a may perform the operations
described above with reference to FIG. 5. The transmitter 515-a may
transmit signals received from other components of UE 115-e. The
transmitter 515-a may illustrate aspects of a transceiver 835
described with reference to FIG. 8.
[0130] The TDD module 605 may identify a TDD configuration of a
carrier as described above with reference to FIGS. 2-4.
Additionally or alternatively, the TDD module 605 may identify a
downlink TTI of a TDD configured carrier. The TDD module 605 may
further coordinate communications based at least in part on the
indication of the downlink TTI and the indication of the uplink
TTI.
[0131] Additionally or alternatively, the TDD module 605 may
receive a set of TBs during the downlink TTI. The downlink TTI may
include a variable TTI. The TDD module 605 may determine HARQ
feedback for each TB of the set of TBs. A number of TBs in the set
may be based at least in part on the duration of the downlink TTI.
The TDD module 605, such as with the transmitter 515-a, may
transmit the HARQ feedback for at least one TB of the set of TBs
during the uplink TTI. In some examples, each TB may include a
number of CBs, which may be based on the size of the TB. The TDD
module 605 may thus determine HARQ feedback for the a number of
CBs. The TDD module 605-a, in combination with transmitter 515-a,
for example, may thus transmit HARQ feedback for one or several CBs
during the uplink TTI.
[0132] The PDFICH/PUFICH module 620, in combination with receiver
505-a, for example, may receive a first multiplexing format signal
from a serving cell of the carrier, the first multiplexing format
signal indicating a first multiplexing configuration of a first TTI
as described above with reference to FIGS. 2-4. For example, the
PDFICH/PUFICH module 620 may be configured to receive a PDFICH and
identify a first multiplexing configuration based on the PDFICH. In
some cases, the first multiplexing configuration is further based
on a DL grant. The PDFICH/PUFICH module 620 may receive or identify
an indication of a duration of the downlink TTI, which may be
during the downlink TTI. The PDFICH/PUFICH module 620 may receive
or identify an indication of a duration of an uplink TTI that
follows the downlink TTI. The indication of the uplink TTI duration
may be received during the downlink TTI. In some cases, the
indication of the duration of the uplink TTI may indicate that the
duration of the uplink TTI is zero. The downlink TTI duration and a
subsequent downlink TTI duration may form a downlink burst that is
time division multiplexed on resources of the TDD configured
carrier.
[0133] The PDFICH/PUFICH module 620 may, in combination with
receiver 505-a, for example, receive a second multiplexing format
signal from the serving cell indicating a second multiplexing
configuration of a second TTI, and the second multiplexing
configuration may be different from the first multiplexing
configuration as described above with reference to FIGS. 2-4. The
first multiplexing configuration may include a first TTI length for
the first TTI and the second multiplexing configuration may include
a second TTI length for the second TTI. For example, in one
embodiment the PDFICH/PUFICH module 620 may be configured to
receive a PUFICH and identify a TTI length of an UL TTI. In another
embodiment, the PDFICH/PUFICH module 620 may be configured to
receive a second PDFICH and identify a second multiplexing
configuration for a DL TTI that is different from the first
multiplexing configuration. The first multiplexing configuration
and the second multiplexing configuration may each correspond to a
multiplexing category selected from a multiplexing category group
consisting of a TDD category, a TDM category, and an FDD
category.
[0134] In some examples, separate PDFICH and PUFICH modules may be
employed, and each may perform various functions of the
PDFICH/PUFICH module 620 illustrated in FIG. 6. Separate PDFICH or
PUFICH modules may, for instance, perform some or all of the
functions described above with reference to the PDFICH/PUFICH
module 620. PDFICH/PUFICH module 620 may thus include a PDFICH
module to identify or receive PDFICH as described herein, and a
PUFICH module may identify or receive PUFICH as described
herein.
[0135] FIG. 7 shows a block diagram 700 of a flexible multiplexing
module 510-b for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure. The
flexible multiplexing module 510-b may be an example of aspects of
a flexible multiplexing module 510 described with reference to
FIGS. 5-6. The flexible multiplexing module 510-b may illustrate
aspects of a processor, such as the processor 805 described with
reference to FIG. 8. The flexible multiplexing module 510-b may
include a TDD module 605-a and a PDFICH/PUFICH module 620-a. In
some examples, the flexible multiplexing module 510-b includes a
PDFICH/PUFICH module 620-a. Each of these modules may perform the
functions described above with reference to FIG. 6. The flexible
multiplexing module 510-b may also include a radio switching module
710 and a DL grant module 715. Each of these components may
illustrate aspects of a processor, such as the processor 805
described with reference to FIG. 8.
[0136] The PDFICH/PUFICH module 620-a may, in conjunction with
other modules of a UE 115 (e.g., UE 115-e of FIG. 6) receive a
third multiplexing format signal from the serving cell indicating a
third TTI length of a third TTI, where the first TTI and the second
TTI are DL TTIs and the third TTI is an UL TTI between the first
TTI and the second TTI, as described above with reference to FIGS.
2-4. Thus, the PDFICH/PUFICH module 620-a may receive a PUFICH and
identify a length of an UL TTI. In some examples, the third
multiplexing format signal indicates an absence of the UL TTI such
that the second TTI may be contiguous to the first TTI. The
PDFICH/PUFICH module 620-a may also receive, in conjunction with
other modules, a fourth multiplexing format signal (e.g., a second
PUFICH) indicating a length of a fourth TTI, where the fourth TTI
is an UL TTI following the second TTI. In some examples, the
PDFICH/PUFICH module 620-a is a submodule of PDFICH/PUFICH module
620-a. Alternatively, PDFICH/PUFICH module 620-a may perform all of
the functions described with reference to the PDFICH/PUFICH module
620-a.
[0137] The radio switching module 710 may switch a radio from a DL
configuration to an UL configuration based on the first
multiplexing format signal and the third multiplexing format signal
as described above with reference to FIGS. 2-4. The radio switching
module 710 may also switch the radio from the UL configuration to
the DL configuration based at least in part on the third
multiplexing format signal. The radio switching module 710 may, in
some examples, switch a radio from a DL configuration to an UL
configuration based on the second multiplexing format signal and
the fourth multiplexing format signal. The radio switching module
710 may also switch the radio from the UL configuration to the DL
configuration based at least in part on the fourth multiplexing
format signal.
[0138] The DL grant module 715 may decode a first DL grant from the
serving cell during (or immediately after) the first TTI, where
receiving the first transmission is based at least in part on the
first DL grant as described above with reference to FIGS. 2-4. The
DL grant module 715 may also decode a second DL grant from the
serving cell during (or immediately after) the second TTI, wherein
the second TTI is a DL TTI. Additionally or alternatively, the DL
grant module 715 may receive a downlink grant during the downlink
TTI, the downlink grant may assign a first set of resources during
the downlink TTI. The DL grant module 715 may receive an additional
downlink grant which may assign a second set of resources during
the downlink TTI.
[0139] In some cases, the first set of resources and the second set
of resources may be frequency division multiplexed during the
downlink TTI. The DL grant module 715 may receive an indication of
a duration of a subsequent downlink TTI that follows the downlink
TTI, wherein the indication of the subsequent TTI duration is
received during the subsequent downlink TTI. The DL grant module
715 may receive an indication of a duration of a subsequent uplink
TTI that follows the subsequent downlink TTI. The indication of the
subsequent uplink TTI duration may be received during the
subsequent downlink TTI. The DL grant module 715 may facilitate
communications based at least in part on the indication of the
subsequent downlink TTI duration or the indication of the
subsequent uplink TTI duration.
[0140] The components of UE 115-d, UE 115-e, or flexible
multiplexing module 510-b may, individually or collectively, be
implemented with at least one application specific integrated
circuit (ASIC) adapted to perform some or all of the applicable
functions in hardware. Alternatively, the functions may be
performed by one or more other processing units (or cores), on at
least one IC. In other embodiments, other types of integrated
circuits may be used (e.g., Structured/Platform ASICs, a field
programmable gate array (FPGA), or another semi-custom IC), which
may be programmed in any manner known in the art. The functions of
each unit may also be implemented, in whole or in part, with
instructions embodied in a memory, formatted to be executed by one
or more general or application-specific processors.
[0141] While much of the discussion of the UEs 115-d and 115-e is
in the context of a TDD system, those skilled in the art will
recognize the applicability of the described techniques to other
systems, including FDD systems.
[0142] FIG. 8 shows a diagram of a system 800 including a UE 115
configured for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure. System
800 may include UE 115-f, which may be an example of a UE 115
described above with reference to FIGS. 1-7. UE 115-f may include a
flexible multiplexing module 810, which may be an example of a
flexible multiplexing module 510 described with reference to FIGS.
5-7. UE 115-f may also include a low power module 825. UE 115-f may
also include components for bi-directional voice and data
communications including components for transmitting communications
and components for receiving communications. For example, UE 115-f
may communicate bi-directionally with UE 115-g or base station
105-c.
[0143] The low power module 825 may configure components of UE
115-f for low power operation, (e.g., based on identifying an
absence of a DL grant for the UE during the first TTI as described
above with reference to FIGS. 2-4). For example, the low power
module 825 may cause the UE 115-f to enter a low power state during
the third TTI based on the third multiplexing format signal (e.g.,
PUFICH) and the absence of the UL grant. The low power module 825
may also identify an absence of a DL grant for the UE during the
second TTI and cause UE 115-f to enter a low power state during the
second TTI based on the second multiplexing format signal (e.g.,
PDFICH) or the absence of the DL grant.
[0144] UE 115-f may also include a processor 805, and memory 815
(including software (SW) 820), a transceiver 835, and one or more
antenna(s) 840, each of which may communicate, directly or
indirectly, with one another (e.g., via buses 845). The transceiver
835 may communicate bi-directionally, via the antenna(s) 840 or
wired or wireless links, with one or more networks, as described
above. For example, the transceiver 835 may communicate
bi-directionally with a base station 105 or another UE 115. The
transceiver 835 may include a modem to modulate the packets and
provide the modulated packets to the antenna(s) 840 for
transmission, and to demodulate packets received from the
antenna(s) 840. While UE 115-f may include a single antenna 840, UE
115-f may also have multiple antennas 840 capable of concurrently
transmitting or receiving multiple wireless transmissions.
[0145] The memory 815 may include random access memory (RAM) and
read only memory (ROM). The memory 815 may store computer-readable,
computer-executable software/firmware code 820 including
instructions that, when executed, cause the processor 805 to
perform various functions described herein (e.g., flexible
multiplexing operation for DL data in TDD systems, etc.).
Alternatively, the software/firmware code 820 may not be directly
executable by the processor 805 but cause a computer (e.g., when
compiled and executed) to perform functions described herein. The
processor 805 may include an intelligent hardware device, (e.g., a
central processing unit (CPU), a microcontroller, an ASIC,
etc.)
[0146] FIG. 9 shows a block diagram 900 of a base station 105-d
configured for flexible multiplexing operation for DL data in
accordance with various aspects of the present disclosure. Base
station 105-d may be an example of aspects of a base station 105
described with reference to FIGS. 1-8. Base station 105-d may
include a receiver 905, a base station flexible multiplexing module
910, or a transmitter 915. Base station 105-d may also include a
processor. Each of these components may be in communication with
one another.
[0147] The receiver 905 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to flexible multiplexing operation for DL data
in TDD systems, etc.). Information may be passed on to the base
station flexible multiplexing module 910, and to other components
of base station 105-d. The receiver 905 may illustrate aspects of a
transceiver 1235 described with reference to FIG. 12.
[0148] The base station flexible multiplexing module 910 may
configure a TDD carrier. In some examples, the base station
flexible multiplexing module 910 may also select a multiplexing
configuration, and, in conjunction with the transmitter 915,
transmit a first multiplexing format signal on the TDD carrier, the
first multiplexing format signal indicating a first multiplexing
configuration of a first TTI, transmit a first data transmission on
the TDD carrier to a first UE during the first TTI based on the
first multiplexing configuration, and transmit a second
multiplexing format signal on the TDD carrier, the second
multiplexing format signal indicating a second multiplexing
configuration of a second TTI. The second multiplexing
configuration may be different from the first multiplexing
configuration, as described above with reference to FIGS. 2-4.
[0149] Additionally or alternatively, the base station flexible
multiplexing module 910, such as along with the transmitter 915,
may transmit an indication of a duration of a downlink TTI, such as
during the downlink TTI, transmit an indication of a duration of an
uplink TTI that follows the downlink TTI, and facilitate
communications based at least in part on the indication of the
downlink TTI and the indication of the uplink TTI. The indication
of the uplink TTI duration may be transmitted during the downlink
TTI. The base station flexible multiplexing module 910 may be an
aspect of a processor, such as the processor 1205 described with
reference to FIG. 12.
[0150] The transmitter 915 may transmit signals received from other
components of base station 105-d. In some embodiments, the
transmitter 915 may be collocated with the receiver 905 in a
transceiver module. The transmitter 915 may include a single
antenna, or it may include a plurality of antennas. In some
examples, the transmitter 915 may transmit a first data
transmission on the TDD carrier to a first UE during the first TTI
based on the first multiplexing configuration. In some examples,
the transmitter 915 may transmit a second data transmission to a
second UE during the second TTI based on the second multiplexing
configuration and the second DL grant. The transmitter 915 may also
transmit a second data transmission to the second UE during the
first TTI using the second set of frequency tones, wherein the
first data transmission utilizes the first set of frequency tones.
The transmitter 915 may illustrate aspects of a transceiver 1235
described with reference to FIG. 12.
[0151] FIG. 10 shows a block diagram 1000 of a base station 105-e
for flexible multiplexing operation for DL data in accordance with
various aspects of the present disclosure. Base Station 105-e may
be an example of aspects of a base station 105 described with
reference to FIGS. 1-9. Base Station 105-e may include a receiver
905-a, a base station flexible multiplexing module 910-a, or a
transmitter 915-a. Base Station 105-e may also include a processor.
Each of these components may be in communication with one another.
The base station flexible multiplexing module 910-a may also
include a BS TDD module 1005 and a BS PDFICH/PUFICH module 1020.
Each of these components may illustrate aspects of a processor,
such as the processor 1205 described with reference to FIG. 12.
[0152] The receiver 905-a may receive information which may be
passed on to base station flexible multiplexing module 910-a, and
to other components of base station 105-e. The receiver 905-a may
illustrate aspects of a transceiver 1235 described with reference
to FIG. 12. The base station flexible multiplexing module 910-a may
perform the operations described above with reference to FIG. 9.
The base station flexible multiplexing module 910-a may be an
aspect of a processor, such as the processor 1205 described with
reference to FIG. 12. The transmitter 915-a may transmit signals
received from other components of base station 105-e. The
transmitter 915-a may illustrate aspects of a transceiver 1235
described with reference to FIG. 12.
[0153] The BS TDD module 1005 may configure a TDD carrier as
described above with reference to FIGS. 2-4. The BS TDD module 1005
may further coordinate communications based at least in part on the
indication of the downlink TTI and the indication of the uplink
TTI.
[0154] Additionally or alternatively, the BS TDD module 1005 may,
in combination with transmitter 915-a, for example, transmit a set
of TBs during the downlink TTI. The downlink TTI may include a
variable TTI. The BS TDD module 1005 may determine, or receive,
HARQ feedback for each TB of the set of TBs. A number of TBs in the
set may be based at least in part on the duration of the downlink
TTI. The BS TDD module 1005 may receive the HARQ feedback for at
least one TB of the set of TBs during the uplink TTI.
[0155] The BS PDFICH/PUFICH module 1020 may transmit a first
multiplexing format signal on the TDD carrier, the first
multiplexing format signal indicating a first multiplexing
configuration of a first TTI as described above with reference to
FIGS. 2-4. For example, the BS PDFICH/PUFICH module 1020 may be
configured to select a TDD, TDM, or FDM multiplexing configuration
based on latency and efficiency parameters. Then BS PDFICH/PUFICH
module 1020 may be configured to transmit the first multiplexing
format signal (e.g., PDFICH) together with a DL grant according to
the selected first multiplexing configuration.
[0156] Additionally or alternatively, the BS PDFICH/PUFICH module
1020 may identify a downlink TTI of a TDD configured carrier or
prepare an indicator of a downlink TTI of a TDD configured carrier.
The BS PDFICH/PUFICH module 1020 may transmit or identify an
indication of a duration of the downlink TTI, such as during the
downlink TTI. The BS PDFICH/PUFICH module 1020 may transmit or
identify an indication of a duration of an uplink TTI that follows
the downlink TTI. The indication of the uplink TTI duration may be
transmitted during the downlink TTI. In some cases, the indication
of the duration of the uplink TTI may indicate that the duration of
the uplink TTI is zero. The downlink TTI duration and a subsequent
downlink TTI duration may form a downlink burst that is time
division multiplexed on resources of the TDD configured
carrier.
[0157] The BS PDFICH/PUFICH module 1020 may transmit a second
multiplexing format signal on the TDD carrier, the second
multiplexing format signal indicating a second multiplexing
configuration of a second TTI, the second multiplexing
configuration different from the first multiplexing configuration
as described above with reference to FIGS. 2-4. In some examples,
the first multiplexing configuration includes a first TTI length
for the first TTI and the second multiplexing configuration
comprises a second TTI length for the second TTI. The first
multiplexing configuration and the second multiplexing
configuration may each correspond to a multiplexing category
selected from a multiplexing category group consisting of a TDD
category, a TDM category, and an FDD category. In some embodiments,
the BS PDFICH/PUFICH module 1020 may be configured to select a
second multiplexing configuration (e.g., TDD, TDM, or FDM)
different from the first multiplexing configuration based on
updated latency and efficiency parameters. Then BS PDFICH/PUFICH
module 1020 may be configured to transmit the second multiplexing
format signal (e.g., PDFICH or PUFICH) together with a DL or UL
grant according to the selected first multiplexing
configuration.
[0158] In some examples, separate BS PDFICH and BS PUFICH modules
may be employed, and each may perform various functions of the BS
PDFICH/PUFICH module 1020 illustrated in FIG. 10. Separate BS
PDFICH or BS PUFICH modules may, for instance, perform some or all
of the functions described above with reference to the BS
PDFICH/PUFICH module 1020. BS PDFICH/PUFICH module 1020 may thus
include a BS PDFICH module to identify or transmit PDFICH as
described herein, and a BS PUFICH module may identify or transmit
PUFICH as described herein.
[0159] FIG. 11 shows a block diagram 1100 of a base station
flexible multiplexing module 910-b for flexible multiplexing
operation for DL data in accordance with various aspects of the
present disclosure. The base station flexible multiplexing module
910-b may be an example of aspects of a base station flexible
multiplexing module 910 described with reference to FIGS. 9-10. The
base station flexible multiplexing module 910-b may include a BS
TDD module 1005-a and a BS PDFICH/PUFICH module 1020-a. In some
examples, the base station flexible multiplexing module 910-b
includes a BS PDFICH/PUFICH module 1020-a. Each of these modules
may perform the functions described above with reference to FIG.
10. The base station flexible multiplexing module 910-b may also
include a BS DL grant module 1110.
[0160] The BS PDFICH/PUFICH module 1020-a may, in conjunction with
other modules, transmit a third multiplexing format signal
indicating a third TTI length of a third TTI, wherein the first TTI
and the second TTI are DL TTIs and the third TTI is an UL TTI
between the first TTI and the second TTI as described above with
reference to FIGS. 2-4. In some examples, the third multiplexing
format signal indicates an absence of the UL TTI such that the
second TTI may be contiguous to the first TTI. The BS PDFICH/PUFICH
module 1020-a may also transmit a fourth multiplexing format signal
indicating a fourth TTI length of a fourth TTI, wherein the fourth
TTI is an UL TTI following the second TTI. In some examples, the BS
PDFICH/PUFICH module 1020-a is a submodule of BS PDFICH/PUFICH
module 1020-a. Alternatively, BS PDFICH/PUFICH module 1020-a may
perform all of the functions described with reference to the BS
PDFICH/PUFICH module 1020-a.
[0161] The BS DL grant module 1110 may transmit a second DL grant
to a second UE during the second TTI as described above with
reference to FIGS. 2-4. The BS DL grant module 1110 may also
transmit a first DL grant to the first UE during the first TTI. The
BS DL grant module 1110 may also transmit a second DL grant to a
second UE during the first TTI, wherein the first DL grant
indicates a first set of frequency tones and the second DL grant
indicates a second set of frequency tones.
[0162] Additionally or alternatively, the BS DL grant module 1110
may transmit a downlink grant during the downlink TTI, the downlink
grant may assign a first set of resources during the downlink TTI.
The BS DL grant module 1110 may transmit an additional downlink
grant which may assign a second set of resources during the
downlink TTI. In some cases, the first set of resources and the
second set of resources may be frequency division multiplexed
during the downlink TTI. The BS DL grant module 1110 may transmit a
subsequent downlink grant during a subsequent downlink TTI which
follows the downlink TTI. The BS DL grant module 1110 may transmit
an indication of a duration of the subsequent downlink TTI during
the subsequent downlink TTI. The BS DL grant module 1110 may
transmit an indication of a duration of a subsequent uplink TTI
that follows the subsequent downlink TTI. The indication of the
subsequent uplink TTI duration may be transmitted during the
subsequent downlink TTI. The BS DL grant module 1110 may facilitate
communications based at least in part on the subsequent downlink
grant, the indication of the subsequent downlink TTI duration, or
the indication of the subsequent uplink TTI duration.
[0163] The components of base station 105-d, base station 105-e, or
base station flexible multiplexing module 910-b may, individually
or collectively, be implemented with at least one ASIC adapted to
perform some or all of the applicable functions in hardware.
Alternatively, the functions may be performed by one or more other
processing units (or cores), on at least one IC. In other
embodiments, other types of integrated circuits may be used (e.g.,
Structured/Platform ASICs, an FPGA, or another semi-custom IC),
which may be programmed in any manner known in the art. The
functions of each unit may also be implemented, in whole or in
part, with instructions embodied in a memory, formatted to be
executed by one or more general or application-specific processors.
While much of the discussion of the base stations 105-d and 105-e
is in the context of a TDD system, those skilled in the art will
recognize the applicability of the described techniques to other
systems, including FDD systems.
[0164] FIG. 12 shows a diagram of a system 1200 including a base
station 105 configured for flexible multiplexing operation for DL
data in accordance with various aspects of the present disclosure.
System 1200 may include base station 105-f, which may be an example
of a base station 105 described above with reference to FIGS. 1-11.
Base Station 105-f may include a base station flexible multiplexing
module 1210, which may be an example of a base station flexible
multiplexing module 910 described with reference to FIGS. 9-11.
Base Station 105-f may also include components for bi-directional
voice and data communications including components for transmitting
communications and components for receiving communications. For
example, base station 105-f may communicate bi-directionally with
UE 115-h or UE 115-i.
[0165] In some cases, base station 105-f may have one or more wired
backhaul links. Base station 105-f may have a wired backhaul link
(e.g., 51 interface, etc.) to the core network 130. Base station
105-f may also communicate with other base stations 105, such as
base station 105-m and base station 105-n via inter-base station
backhaul links (e.g., an X2 interface). Each of the base stations
105 may communicate with UEs 115 using the same or different
wireless communications technologies. In some cases, base station
105-f may communicate with other base stations such as 105-m or
105-n utilizing base station communications module 1225.
Additionally or alternatively, base station communications module
1225 may provide an X2 interface within an LTE/LTE-A wireless
communication network technology to provide communication between
some of the base stations 105. In some embodiments, base station
105-f may communicate with other base stations through core network
130. In some cases, base station 105-f may communicate with the
core network 130 through network communications module 1230.
[0166] The base station 105-f may include a processor 1205, memory
1215 (including software (SW) 1220), transceiver 1235, and
antenna(s) 1240, which each may be in communication, directly or
indirectly, with one another (e.g., over bus system 1245). The
transceiver 1235 may be configured to communicate bi-directionally,
via the antenna(s) 1240, with the UEs 115, which may be multi-mode
devices. The transceiver 1235 (or other components of base station
105-f) may also be configured to communicate bi-directionally, via
the antennas 1240, with one or more other base stations (not
shown). The transceiver 1235 may include a modem configured to
modulate the packets and provide the modulated packets to the
antennas 1240 for transmission, and to demodulate packets received
from the antennas 1240. The base station 105-f may include multiple
transceivers 1235, each with one or more associated antennas 1240.
The transceiver module may be an example of a combined receiver 905
and transmitter 915 of FIG. 9.
[0167] The memory 1215 may include RAM and ROM. The memory 1215 may
also store computer-readable, computer-executable software code
1220 containing instructions that are configured to, when executed,
cause the processor module 1210 to perform various functions
described herein (e.g., flexible multiplexing operation for DL data
in TDD systems, selecting coverage enhancement techniques, call
processing, database management, message routing, etc.).
Alternatively, the software code 1220 may not be directly
executable by the processor 1205 but be configured to cause the
computer, e.g., when compiled and executed, to perform functions
described herein. The processor 1205 may include an intelligent
hardware device, e.g., a CPU, a microcontroller, an ASIC, etc. The
processor 1205 may include various special purpose processors such
as encoders, queue processing modules, base band processors, radio
head controllers, digital signal processor (DSPs), and the
like.
[0168] The base station communications module 1225 may manage
communications with other base stations 105. The communications
management module may include a controller or scheduler for
controlling communications with UEs 115 in cooperation with other
base stations 105. For example, the base station communications
module 1225 may coordinate scheduling for transmissions to UEs 115
for various interference mitigation techniques such as beamforming
or joint transmission.
[0169] As discussed above, various examples provide communications
in a wireless communications system, such as wireless
communications system 100 of FIG. 1, that utilize variable TTIs.
FIG. 13 is a block diagram 1300 conceptually illustrating an
example of radio frames and different subframes that may be
transmitted using different cells of a wireless communication
system, such as wireless communications system 100 of FIG. 1, in
accordance with aspects of the present disclosure. The radio frames
of FIG. 13 may be transmitted using portions of the wireless
communications system 100 described with reference to FIG. 1
between one or more base stations 105 and one or more UEs 115, for
example. In this example, a legacy PCell transmission 1310 may
include a TDD frame that include ten 1 ms subframes, including
downlink subframes 1325, special subframes 1330, and uplink
subframes 1335. The downlink subframes 1325, special subframes
1330, and uplink subframes 1335 may include a subframe structure
defined according to established LTE standards, which may include
14 symbols 1366 within each 1 ms subframe. In some examples,
downlink subframes 1325 may include downlink orthogonal frequency
division multiplexing (OFDM) symbols, uplink subframes may include
single carrier frequency division multiplexing (SC-FDM) symbols,
and special subframes 1330 may include both uplink SC-FDM symbols
and downlink OFDM symbols.
[0170] In the example of FIG. 13, SCell transmissions 1320 may
include low latency or burst mode transmissions that may replace
the legacy frame structure with a TDD-based frame structure that
allows for dynamic switching between downlink and uplink symbols
and for variable TTI lengths. While the example of FIG. 13 shows
the low latency or burst mode transmissions on a SCell, it will be
understood that such transmission structures, as well as various of
the techniques and principles described herein, may be implemented
in other transmissions, such as within one or more burst mode
subframes of a legacy LTE frame, in other PCell transmissions, in
licensed or unlicensed spectrum or the like. In the example of FIG.
13, the SCell may be an eCC, and the SCell transmissions 1320,
which may be referred to as eCC transmissions, may include
designated downlink symbols 1340 and designated uplink symbols
1360, and flexible symbols 1345 that may be allocated as uplink or
downlink symbols based on particular traffic needs.
[0171] The designated downlink symbols 1340 and designated uplink
symbols 1360 may be provided to enable various radio resource
management (RRM) measurements, synchronization, CSI feedback,
random access channel (RACH) and scheduling request (SR)
communications, for example. The designated downlink symbols 1340
and designated uplink symbols 1360 may be configured by a base
station, such as base stations 105 of FIG. 1, and may be
communicated to one or more UEs, such as UEs 115 of FIG. 1, via RRC
signaling, a system information block (SIB), or physical downlink
control channel (PDCCH) signaling. As mentioned, flexible symbols
1345 may be switched to be uplink or downlink symbols, and the
indication of such configurations may be provided by a base station
in an allocation of uplink or downlink resources that is provided
to a UE 115. Based on such an allocation, the UE may determine that
a certain number of symbols 1340, 1345, 1360 may be allocated for
communications between the UE and the base station.
[0172] With such dynamic switching of symbols, a base station and
UE are not required to look ahead in terms of a number of uplink or
downlink subframes for an entire radio frame, but may determine
particular resource allocations in a dynamic and flexible manner.
The number of resources allocated for a particular UE may be
determined, for example, on an amount of data to be transmitted
between the UE and the base station, and a latency requirement or
quality of service (QoS) requirement associated with the data. In
some examples, each of the symbols 1340, 1345, and 1360 may have a
reduced symbol duration relative to the legacy OFDM or SC-FDM
symbols (e.g., symbols 1366), and in some examples have a symbol
duration of 11.36 .mu.s per symbol, including a useful symbol
duration of 8.33 .mu.s and a cyclic prefix duration of 2.03 .mu.s.
Symbols 1340, 1345, and 1360 may have increased tone spacing for
subcarriers relative to legacy symbols, and in some examples have a
tone spacing of 120 kHz, and utilize a relatively wide bandwidth
(e.g., 80 MHz).
[0173] Such shortened symbol duration and dynamic switching between
downlink and uplink communications may allow for reduced ACK/NACK
turn-around time, and may thus provide relatively low latency
transmissions of data. In some examples, delay sensitive data may
be transmitted using SCell transmissions 1320, while other data
that is not as delay sensitive may be transmitted using PCell
transmissions 1310. In some examples, a number of symbols 1340,
1345, and 1360 may be allocated to a first UE for a first time
period (T.sub.1) 1365, and may be allocated to the first UE or one
or more other UEs during a second time period (T.sub.2) 1370 and
third time period (T.sub.3) 1375. The length of such time periods
1365, 1370, 1375 may be determined according to a variety of
factors including, for example, an amount of data to be
transmitted, a QoS associated with the data, a delay requirement of
the data, a number of other UEs present, or channel conditions, to
name but a few.
[0174] With reference now to FIG. 14 a block diagram 1400
conceptually illustrating an example of eCC transmissions is
discussed. In the example of FIG. 14, eCC transmissions 1420 may
include a number of symbols allocated as uplink or downlink
symbols. Such eCC transmissions 1420 may be transmitted using
different cells of a wireless communication system, such as
wireless communications system 100 of FIG. 1, in accordance with
aspects of the present disclosure. In some examples, eCC
transmissions 1420 are transmitted on a SCell such as discussed
above with respect to FIG. 13. In the example of FIG. 14, a first
time period (T.sub.1) 1440 may include a downlink grant of nine
symbols 1430. In this example, an initial downlink symbol 1430 may
include control information 1435 that may indicate resource
allocations for an upcoming time period (e.g., T.sub.1 1440).
[0175] In some examples, the control information 1435 may include a
downlink grant of resources to a UE that include the subsequent
symbols 1430. In this example, a subsequent transmission of control
information 1435 may include an uplink grant of eight uplink
symbols 1445. A blank symbol 1455 may be included between a
downlink symbol 1430 and an uplink symbol 1445, to allow time for
switching at a UE. In some examples, bundles of symbols 1430, 1445
may be allocated to a UE by a base station, with a length of such
bundles controlled by control information (e.g., dynamic grants)
1435. A relatively large number of symbols may be allocated to
provide enhanced efficiency in some examples that are somewhat less
delay sensitive.
[0176] In other examples, if data transmissions are relatively
delay sensitive, dynamic grants to a particular UE may be
relatively short in order to provide for reduced ACK/NACK
turn-around times. FIG. 15 illustrates an example 1500 of
relatively short grants. In this example, eCC transmissions 1520
may include resource allocations of only one or two symbols. The
eCC transmissions 1520 of FIG. 15 may be transmitted using a
wireless communication system, such as wireless communications
system 100 of FIG. 1, in accordance with aspects of the present
disclosure.
[0177] In some examples, eCC transmissions 1520 are transmitted on
a SCell, such as discussed above with respect to FIGS. 13 and 14.
In this example, control information 1535 in the initial downlink
symbol 1525 may include a downlink grant of one symbol (e.g., TTI=1
symbol) and an uplink grant of one symbol (e.g., TTI=1 symbol). The
uplink grant, in various examples, may take effect at a two symbol
minimum from the receipt of the control information 1535, in order
to accommodate blank symbol 1530 and allow for switching at the UE
to transmit uplink symbol 1540. In this example, eCC transmissions
1520 include a transmission of second control information 1550
which, in this example, is a downlink grant for two symbols (e.g.,
TTI=2 symbols), with third control information 1555 providing a
subsequent uplink grant which may have a TTI of one or more uplink
symbols 1540. The time periods or TTIs 1560 are 2 symbols.
[0178] As mentioned above, various examples provide that feedback
for several downlink TTIs, or several UEs, may be transmitted
during a single uplink TTI. FIG. 16 illustrates an example 1600 of
feedback for a carrier employing variable TTI in accordance with
various aspects of the present disclosure. In this example,
feedback for downlink eCC transmissions 1620 may be transmitted at
the first uplink symbol opportunity. The eCC transmissions 1620 of
FIG. 16 may be transmitted using a wireless communication system,
such as wireless communications system 100 of FIG. 1, in accordance
with aspects of the present disclosure. In some examples, eCC
transmissions 1620 are transmitted on a SCell, such as discussed
above with respect to FIGS. 13-15. The eCC transmission 1620 may
include uplink symbols 1640 and downlink symbols 1645. In this
example, a downlink grant 1650 may be for four (4) downlink symbols
1645, such that a downlink TTI 1660 is equal to four (4) symbols. A
downlink grant 1650 may, however, be for any number of symbols,
such that the downlink TTI 1660 is variable. Or, in some cases, a
downlink grant 1650 may assign a pre-determined number of downlink
symbols 1645. For example, a system may be configured such that
each downlink grant 1650 assigns one of several pre-determined
number of downlink symbols (e.g., one (1), five (5), ten (10),
etc.).
[0179] An uplink grant 1665 received during the downlink TTI 1660
may grant resources for feedback, such as ACK/NACK 1670 block
during the first uplink symbol 1640 following the downlink TTI
1660. A UE may thus transmit feedback (ACK/NACK 1670) as a block
for all TBs of the preceding downlink symbol burst--e.g., the
downlink TTI 1660. In some cases, several different UEs will be
scheduled downlink resources, and will receive downlink symbols
1645, before an uplink symbol 1640 is available. Accordingly, each
UE may transmit feedback a the first uplink symbol opportunity. An
uplink TTI may include a single symbol period, or it may include
several symbol periods. In either case, feedback (e.g., ACK/NACK
1670) for one or several TBs may be transmitted over the duration
of the uplink TTI, such that the feedback transmission spans a
number of uplink symbols.
[0180] Each TB of a downlink TTI 1660 may have a corresponding HARQ
process, such that, within the ACK/NACK 1670 block, an ACK or NACK
may be transmitted for each TB. Thus, if a single UE receives four
(4) TBs during the downlink TTI 1660, the ACK/NACK 1670 block may
include four (4) ACK/NACKs, one for each TB. Likewise, if one UE
receives two (2) TBs during two symbols of the downlink TTI 1660,
and another UE receives two (2) TBs during two symbols of the
downlink TTI 1660, the ACK/NACK 1670 block may include four (4)
ACK/NACKs, one for each TB. HARQ feedback transmitted in ACK/NACK
1670 block may thus be determined, in part, according to a time
duration of the variable TTI duration. Each TB may include one or
several code blocks. So, in some examples, a TB may include
multiple code blocks and HARQ feedback for the TB may include
feedback for multiple code blocks. But in other examples, a TB may
include a single code block; and HARQ feedback for a TB may include
feedback for a single code block.
[0181] In some examples, a blank symbol or switching interval 1675
may be included within the eCC transmissions 1620. This switching
interval 1675 may provide a UE time to switch from a receive mode
to a transmit mode. A UE may thus receive an uplink grant 1665 for
a first uplink symbol 1640 following a switching interval 1675. Or,
in some examples, a switching interval may itself convey to a UE
that an uplink symbol 1640 is eminent, and the UE may transmit
feedback on the next uplink symbol 1640 without the necessity of an
uplink grant.
[0182] A maximum number of HARQ processes may be determined by the
maximum number of ACK/NACK 1670 bits that can be reported in a
single uplink symbol. That is, in some cases, uplink resources
available for feedback may be limited. In such cases, feedback
(e.g., ACKs/NACKs) for several TBs may be bundled. For instance, a
single ACK/NACK may provide feedback for a number of TBs.
[0183] While not shown here, in some examples, an ACK/NACK 1670
block may span several uplink symbols. An uplink TTI may, for
instance, be composed of several uplink symbols 1640, and an
ACK/NACK 1670 block may be transmitted in more than one uplink
symbol 1640 of the uplink TTI.
[0184] Additionally or alternatively, a base station may convey to
a UE whether an uplink transmission was correctly received using an
implicit ACK/NACK in an uplink grant. For example, depending on
whether an uplink grant is for a new uplink transmission or for a
retransmission, a UE may infer whether a prior uplink transmission
was received correctly. So, in the example of FIG. 16, if the
uplink grant 1665 includes a grant for a new transmission (e.g., a
new TB) in an uplink symbol 1640, then a UE may infer than a prior
uplink transmission was successful. Thus, the grant may imply an
ACK. But if the uplink grant 1665 includes a grant for a
retransmission of a prior uplink transmission, then the grant may
imply a NACK, and the UE may retransmit. This implicit ACK/NACK may
allow the system to avoid physical hybrid indicator channel (PHICH)
transmissions, thus conserving both time and frequency
resources.
[0185] Next, FIG. 17 illustrates a portion of a carrier 1700 with
uplink channel multiplexing for providing feedback for a variable
TTI, in accordance with various aspects of the present disclosure.
The carrier 1700 may be transmitted using a wireless communication
system, such as wireless communications system 100 of FIG. 1. In
some examples, the carrier 1700 is an SCell, such as discussed
above with respect to FIGS. 13-16. The carrier 1700 has a bandwidth
1705 (e.g., 80 MHz), and the portion illustrated is of a variable
TTI 1707. The variable TTI 1707 may include signals or channels
having one symbol width 1710 or that are several symbols wide 1715.
The carrier 1700 may include group reference signals (GRS) 1720 for
several UEs, such as the UEs 115 of FIG. 1. It may also include
physical uplink control channel (PUCCH) GRS 1730 and physical
uplink shared channel (PUCCH) 1725 (e.g., data channels) for
several UEs. Additionally or alternatively, the carrier 1700 may
include a number of PUCCHs 1735, 1740, 1745, 1750, or 1755 from
different UEs. Each of these various signals and channels may be
time division multiplexed (TDM), frequency division multiplexed
(FDM), or code division multiplexed (CDM) with one another.
[0186] For example, PUCCHs 1735, 1740, and 1745, each transmitted
from a different UE on a different interlace, may be FDM with
PUSCHs 1725 of various UEs. The frequency allocation for each PUCCH
may, for example, be tied to an uplink burst length (e.g., uplink
TTI). Likewise, PUSCHs 1725 from various UEs may be FDM with one
another. An uplink grant, such as the uplink grant described with
reference to FIG. 15, may carry a resource block (RB) allocation
for a particular PUSCH 1725 region for a given UE. The PUCCHs 1735,
1740, and 1745 may be CDM within the same resource. GRS 1720 and
PUCCH GRS 1730 may be transmitted upfront (e.g., TDM earlier in
time) within each FDM frequency region. For PUSCHs 1725, the
presence (e.g., the location) of a GRS 1720 is indicated in an
uplink grant, like the uplink grant described with reference to
FIG. 15.
[0187] While the carrier 1700 is shown and described generally in
terms of FDM, at least with respect to PUCCH and PUSCH, a TDM
scheme may also be employed. In some cases, FDM may provide for
increased reference signal (RS) efficiency; but in other examples,
TDM may be preferable. Accordingly, one or several PUCCH may be TDM
with PUSCH.
[0188] Turning next to FIG. 18, shown is a block diagram 1800 of a
UE 115-j configured for feedback for variable TTI, in accordance
with various aspects of the present disclosure. UE 115-j may be an
example of aspects of a UE 115, and may employ techniques,
described with reference to FIGS. 1-17. UE 115-j may include a
receiver 1805, a feedback module 1810, or a transmitter 1815. UE
115-j may also include a processor. Each of these components may be
in communication with one another.
[0189] The receiver 1805 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to HARQ for variable TTI, etc.). Information
may be passed on to the feedback module 1810, and to other
components of UE 115-j. In some examples, the receiver 1805 may
receive a plurality of TBs in a variable downlink transmission TTI.
The receiver 1805 may also receive a grant for a second uplink TB
or for a retransmission of the first uplink TB. The receiver 1805
may represent examples of aspects of a transceiver 2135 described
with reference to FIG. 21.
[0190] The feedback module 1810 may receive, in combination with
the receiver 1805, a plurality of TBs in a variable downlink
transmission TTI, determine HARQ feedback for each TB of the
plurality of TBs, where a number of TBs in the plurality is based
on a time duration of the variable downlink TTI, and cause to be
transmitted, in combination with the transmitter in an uplink TTI
following the downlink TTI, the HARQ feedback for each TB. The
feedback module 1810 may be an aspect of a processor, such as the
processor 2105 described with reference to FIG. 21.
[0191] The transmitter 1815 may transmit signals received from
other components of UE 115-j. In some examples, the transmitter
1815 may be collocated with the receiver 1805 in a transceiver
module. The transmitter 1815 may include a single antenna, or it
may include a plurality of antennas. In some examples, the
transmitter 1815 may transmit a first uplink TB on resources or an
uplink TTI. The transmitter 1815 may represent examples of aspects
of a transceiver 2135 described with reference to FIG. 21.
[0192] FIG. 19 shows a block diagram 1900 of a UE 115-k for
feedback for variable TTI in accordance with various aspects of the
present disclosure. UE 115-k may be an example of aspects of a UE
115, and may employ techniques, described with reference to FIGS.
1-18. UE 115-k may include a receiver 1805-a, a feedback module
1810-a, or a transmitter 1815-a. UE 115-k may also include a
processor. Each of these components may be in communication with
one another. The feedback module 1810-a may also include a HARQ
module 1905 and a UL timing determination module 1910. Each of
these components may illustrate aspects of a processor, such as the
processor 2105 described with reference to FIG. 21.
[0193] The receiver 1805-a may receive information which may be
passed on to feedback module 1810-a, and to other components of UE
115-k. The receiver 1805-a may represent examples of aspects of a
transceiver 2135 described with reference to FIG. 21. The feedback
module 1810-a may perform the operations described above with
reference to FIG. 18. The feedback module 1810-a may be an aspect
of a processor, such as the processor 2105 described with reference
to FIG. 21. The transmitter 1815-a may transmit signals received
from other components of UE 115-k. The transmitter 1815-a may
represent examples of aspects of a transceiver 2135 described with
reference to FIG. 21.
[0194] The HARQ module 1905 may determine HARQ feedback for each TB
of the plurality of TBs, as described above with reference to FIGS.
13-17. In some examples, the HARQ feedback for each TB includes an
ACK or NACK for each TB of the plurality of TBs. In some examples,
the HARQ feedback for each TB includes HARQ feedback from a first
UE, and the uplink TTI may be common to a second UE.
[0195] The UL timing determination module 1910 may transmit, in an
uplink TTI following the downlink TTI, the HARQ feedback for each
TB, as described above with reference to FIGS. 13-17. In some
examples, an uplink grant may be received in a portion of the
variable downlink TTI, and the HARQ feedback for each TB may be
transmitted at a time based on the received uplink grant. In some
examples, the HARQ feedback for each TB may be transmitted at a
time based on an identified switching interval, which may precede
the uplink TTI. In some examples, the HARQ feedback for each TB may
be transmitted at least during an initial symbol period of the
uplink TTI, and the HARQ feedback may occupy additional symbol
periods.
[0196] FIG. 20 shows a block diagram 2000 of a feedback module
1810-b for feedback for variable TTI in accordance with various
aspects of the present disclosure. The feedback module 1810-b may
be an example of aspects of a feedback module 1810 described with
reference to FIGS. 18-19. The feedback module 1810-b may include a
HARQ module 1905-a and a UL timing determination module 1910-a.
Each of these modules may perform the functions described above
with reference to FIG. 19. The feedback module 1810-b may also
include a HARQ resource module 2005, a feedback bundle module 2010,
a switching interval module 2015, and a feedback determination
module 2020.
[0197] The HARQ resource module 2005 may determine that a maximum
number of HARQ resources for the uplink TTI is met or exceeded as
described above with reference to FIGS. 13-17. An a UE 115 may
prepare feedback accordingly. For instance, the feedback bundle
module 2010 may bundle HARQ feedback for two or more TBs of the
plurality of TBs according to the maximum number of HARQ resources
as described above with reference to FIGS. 13-17.
[0198] In some examples, the switching interval module 2015 may
identify a switching interval following the downlink TTI as
described above with reference to FIGS. 13-17.
[0199] The feedback determination module 2020 may be employed for
uplink feedback. For example, the feedback determination module
2020 may determine that a grant represents an ACK when the grant is
for a second uplink TB as described above with reference to FIGS.
13-17. The feedback determination module 2020 may also determine
that the grant represents a NACK when the grant is for a
retransmission of the first uplink TB.
[0200] The components of UE 115-j, UE 115-k, or feedback module
1810-b may, individually or collectively, be implemented with at
least one application specific integrated circuit (ASIC) adapted to
perform some or all of the applicable functions in hardware.
Alternatively, the functions may be performed by one or more other
processing units (or cores), on at least one IC. In other
embodiments, other types of integrated circuits may be used (e.g.,
Structured/Platform ASICs, a field programmable gate array (FPGA),
or another semi-custom IC), which may be programmed in any manner
known in the art. The functions of each unit may also be
implemented, in whole or in part, with instructions embodied in a
memory, formatted to be executed by one or more general or
application-specific processors.
[0201] FIG. 21 shows a diagram of a system 2100 including a UE 115
configured for feedback for variable TTI in accordance with various
aspects of the present disclosure. System 2100 may include UE
115-m, which may be an example of a UE 115 described above with
reference to FIGS. 1-20. UE 115-m may include a feedback module
2110, which may be an example of a feedback module 1810 described
with reference to FIGS. 18-20. UE 115-m may also include components
for bi-directional voice and data communications including
components for transmitting communications and components for
receiving communications. For example, UE 115-m may communicate
bi-directionally with UE 115-n or base station 105-g.
[0202] UE 115-m may also include a processor 2105, and memory 2115
(including software (SW)) 2120, a transceiver 2135, and one or more
antenna(s) 2140, each of which may communicate, directly or
indirectly, with each other (e.g., via buses 2145). The transceiver
2135 may communicate bi-directionally, via the antenna(s) 2140 or
wired or wireless links, with one or more networks, as described
above. For example, the transceiver 2135 may communicate
bi-directionally with a base station 105 or another UE 115. The
transceiver 2135 may include a modem to modulate the packets and
provide the modulated packets to the antenna(s) 2140 for
transmission, and to demodulate packets received from the
antenna(s) 2140. While UE 115-m may include a single antenna 2140,
UE 115-m may also have multiple antennas 2140 capable of
concurrently transmitting or receiving multiple wireless
transmissions.
[0203] The memory 2115 may include random access memory (RAM) and
read only memory (ROM). The memory 2115 may store
computer-readable, computer-executable software/firmware code 2120
including instructions that, when executed, cause the processor
2105 to perform various functions described herein (e.g., HARQ for
variable TTI, and the like). Alternatively, the software/firmware
code 2120 may not be directly executable by the processor 2105 but
cause a computer (e.g., when compiled and executed) to perform
functions described herein. The processor 2105 may include an
intelligent hardware device, (e.g., a central processing unit
(CPU), a microcontroller, an ASIC, etc.).
[0204] FIG. 22 shows a block diagram 2200 of a base station 105-h
configured for feedback for variable TTI in accordance with various
aspects of the present disclosure. Base station 105-h may be an
example of aspects of a base station 105, and may employ
techniques, described with reference to FIGS. 1-17. Base station
105-h may include a receiver 2205, a base station feedback module
2210, or a transmitter 2215. Base station 105-h may also include a
processor. Each of these components may be in communication with
one another.
[0205] The receiver 2205 may receive information such as packets,
user data, or control information associated with various
information channels (e.g., control channels, data channels, and
information related to HARQ for variable TTI, etc.). Information
may be passed on to the base station feedback module 2210, and to
other components of base station 105-h. The receiver 2205 may
represent examples of aspects of a transceiver 2535 described with
reference to FIG. 25.
[0206] The base station feedback module 2210 may receive, in
combination with the receiver, a first set of HARQ feedback for
each TB of a first plurality of TBs from a first UE during a first
uplink TTI, and receive a second set of HARQ feedback for each TB
of a second plurality of TBs during the first uplink TTI. The base
station feedback module 2210 may be an aspect of a processor, such
as the processor 2505 described with reference to FIG. 25.
[0207] The transmitter 2215 may transmit signals received from
other components of base station 105-h. In some examples, the
transmitter 2215 may be collocated with the receiver 2205 in a
transceiver module. The transmitter 2215 may include a single
antenna, or it may include a plurality of antennas. In some
examples, the transmitter 2215 may transmit an uplink grant to a
UE. The transmitter 2215 may represent examples of aspects of a
transceiver 2535 described with reference to FIG. 25.
[0208] FIG. 23 shows a block diagram 2300 of a base station 105-i
for HARQ for variable TTI in accordance with various aspects of the
present disclosure. Base station 105-i may be an example of aspects
of a base station 105, and may employ techniques, described with
reference to FIGS. 1-17 and 22. Base station 105-i may include a
receiver 2205-a, a base station feedback module 2210-a, or a
transmitter 2215-a. Base station 105-h may also include a
processor. Each of these components may be in communication with
one another. The base station feedback module 2210-a may also
include a first feedback reception module 2305, and a second
feedback reception module 2310. Each of these components may
illustrate aspects of a processor, such as the processor 2505
described with reference to FIG. 25.
[0209] The receiver 2205-a may receive information which may be
passed on to base station feedback module 2210-a, and to other
components of base station 105-h. The receiver 2205-a may represent
examples of aspects of a transceiver 2535 described with reference
to FIG. 25. The base station feedback module 2210-a may perform the
operations described above with reference to FIG. 22. The base
station feedback module 2210 may be an aspect of a processor, such
as the processor 2505 described with reference to FIG. 25. The
transmitter 2215-a may transmit signals received from other
components of base station 105-h. The transmitter 2215-a may
represent examples of aspects of a transceiver 2535 described with
reference to FIG. 25.
[0210] The first feedback reception module 2305 may, in conjunction
with the receiver 2205-a, receive a first set of HARQ feedback for
each TB of a first plurality of TBs, which may have been
transmitted using a variable downlink TTI, from a first UE during a
first uplink TTI as described above with reference to FIGS.
13-17.
[0211] The second feedback reception module 2310 may, in
conjunction with the receiver 2205-a, receive a second set of HARQ
feedback for each TB of a second plurality of TBs from a second UE
during the first uplink TTI as described above with reference to
FIGS. 13-17. In some examples, the first and second sets of HARQ
feedback are CDM on a common frequency resource, as described with
reference to FIG. 17.
[0212] FIG. 24 shows a block diagram 2400 of a base station
feedback module 2210-b for feedback for variable TTI in accordance
with various aspects of the present disclosure. The base station
feedback module 2210-b may be an example of aspects of a base
station feedback module 2210, and may employ techniques, described
with reference to FIGS. 22-12. The base station feedback module
2210-b may include a first feedback reception module 2305-a and a
second feedback reception module 2310-a. These modules may perform
the functions described above with reference to FIG. 23. The base
station feedback module 2210-b may also include a FDM PUSCH module
2405, a GRS module 2410, or a TDM PUSCH module 2415.
[0213] The FDM PUSCH module 2405 may receive a first PUSCH from a
first UE during the first uplink TTI, the first PUSCH may be FDM
with several sets of HARQ feedback, as described above with
reference to FIGS. 13-17. The FDM PUSCH module 2405 may receive a
second PUSCH from a second UE during the first uplink TTI, and the
second PUSCH be FDM with several sets of HARQ feedback, as
described above with reference to FIGS. 13-17. The GRS module 2410
may receive group reference signals (GRS) for each of the PUSCH,
and for each sets of HARQ feedback in TTI preceding the first
uplink TTI, as described above with reference to FIGS. 13-17.
[0214] The TDM PUSCH module 2415 may receive a PUSCH on the same
frequency resources as the first and second sets of HARQ feedback,
the PUSCH and several sets of HARQ feedback may be TDM, as
described above with reference to FIGS. 13-17.
[0215] The components of base station 105-h, base station 105-i, or
base station feedback module 2210-b may, individually or
collectively, be implemented with at least one ASIC adapted to
perform some or all of the applicable functions in hardware.
Alternatively, the functions may be performed by one or more other
processing units (or cores), on at least one IC. In other
embodiments, other types of integrated circuits may be used (e.g.,
Structured/Platform ASICs, an FPGA, or another semi-custom IC),
which may be programmed in any manner known in the art. The
functions of each unit may also be implemented, in whole or in
part, with instructions embodied in a memory, formatted to be
executed by one or more general or application-specific
processors.
[0216] FIG. 25 shows a diagram of a system 2500 including a base
station 105 configured for feedback for variable TTI in accordance
with various aspects of the present disclosure. System 2500 may
include base station 105-j, which may be an example of a base
station 105, and may employ techniques, described above with
reference to FIGS. 1-24. Base station 105-j may include a base
station feedback module 2510, which may be an example of a base
station feedback module 2210 described with reference to FIGS.
22-24. Base station 105-j may also include components for
bi-directional voice and data communications including components
for transmitting communications and components for receiving
communications. For example, base station 105-j may communicate
bi-directionally with base station 105-m or base station 105-n.
[0217] In some cases, base station 105-j may have one or more wired
backhaul links. Base station 105-j may have a wired backhaul link
(e.g., 51 interface, etc.) to the core network 130-a. Base station
105-j may also communicate with other base stations 105, such as
base station 105-m and base station 105-n via inter-base station
backhaul links (e.g., an X2 interface). Each of the base stations
105 may communicate with UEs 115 using the same or different
wireless communications technologies. In some cases, base station
105-j may communicate with other base stations such as 105-m or
105-n utilizing base station communication module 2525. In some
examples, base station communication module 2525 may provide an X2
interface within an LTE/LTE-A wireless communication network
technology to provide communication between some of the base
stations 105. Additionally or alternatively, base station 105-j may
communicate with other base stations through core network 130-a. In
some cases, base station 105-j may communicate with the core
network 130-a through network communications module 2530.
[0218] The base station 105-j may include a processor 2505, memory
2515 (including software (SW) 2520), transceiver 2535, and
antenna(s) 2540, which each may be in communication, directly or
indirectly, with one another (e.g., over bus system 2545). The
transceiver 2535 may be configured to communicate bi-directionally,
via the antenna(s) 2540, with the UEs 115, which may be multi-mode
devices. The transceiver 2535 (or other components of the base
station 105-j) may also be configured to communicate
bi-directionally, via the antennas 2540, with one or more other
base stations (not shown). The transceiver 2535 may include a modem
configured to modulate the packets and provide the modulated
packets to the antennas 2540 for transmission, and to demodulate
packets received from the antennas 2540. The base station 105-j may
include multiple transceivers 2535, each with one or more
associated antennas 2540. The transceiver module may be an example
of a combined receiver 2205 and transmitter 2215 of FIG. 22.
[0219] The memory 2515 may include RAM and ROM. The memory 2515 may
also store computer-readable, computer-executable software code
2520 containing instructions that are configured to, when executed,
cause the processor 2505 to perform various functions described
herein (e.g., receive or transmit feedback for variable TTI,
selecting coverage enhancement techniques, call processing,
database management, message routing, etc.). Alternatively, the
software code 2520 may not be directly executable by the processor
2505 but be configured to cause the computer, e.g., when compiled
and executed, to perform functions described herein. The processor
2505 may include an intelligent hardware device, e.g., a CPU, a
microcontroller, an ASIC, etc. The processor 2505 may include
various special purpose processors such as encoders, queue
processing modules, base band processors, radio head controllers,
digital signal processor (DSPs), and the like.
[0220] The base station communication module 2525 may manage
communications with other base stations 105. The base station
communication module 2525 may include a controller or scheduler for
controlling communications with UEs 115 in cooperation with other
base stations 105. For example, the base station communication
module 2525 may coordinate scheduling for transmissions to UEs 115
for various interference mitigation techniques such as beamforming
or joint transmission.
[0221] FIG. 26 shows a flowchart illustrating a method 2600 for
flexible multiplexing operation for DL data in TDD systems in
accordance with various aspects of the present disclosure. The
operations of method 2600 may be implemented by a UE 115 or its
components as described with reference to FIGS. 1-8. For example,
the operations of method 2600 may be performed by the flexible
multiplexing module 510 as described with reference to FIGS. 5-8.
In some examples, a UE 115 may execute a set of codes to control
the functional elements of the UE 115 to perform the functions
described below. Additionally or alternatively, the UE 115 may
perform aspects the functions described below using special-purpose
hardware.
[0222] At block 2605, the UE 115 may identify a downlink TTI of a
TDD configured carrier as described above with reference to FIGS.
2-4. In certain examples, the operations of block 2605 may be
performed by the TDD module 605 as described above with reference
to FIG. 6.
[0223] At block 2610, the UE 115 may receive an indication of a
duration of the downlink TTI during the downlink TTI as described
above with reference to FIGS. 2-4. In certain examples, the
operations of block 2610 may be performed by the PDFICH/PUFICH
module 620 as described above with reference to FIG. 6.
[0224] At block 2615, the UE 115 may receive an indication of a
duration of an uplink TTI that follows the downlink TTI as
described above with reference to FIGS. 2-4. The indication of the
uplink TTI duration may be received during the downlink TTI. In
certain examples, the operations of block 2615 may be performed by
the PDFICH/PUFICH module 620 as described above with reference to
FIG. 6.
[0225] At block 2620, the UE 115 may communicate based at least in
part on the indication of the downlink TTI and the indication of
the uplink TTI as described above with reference to FIGS. 2-4. In
certain examples, the operations of block 2620 may be performed by
the TDD module 605 as described above with reference to FIG. 6.
[0226] In some cases, the method 2600 may further include receiving
a downlink grant during the downlink TTI. The downlink grant may
assign a first set of resources during the downlink TTI. The method
2600 may include receiving an additional downlink grant that
assigns a second set of resources during the downlink TTI. The
first set of resources and the second set of resources may be
frequency division multiplexed during the downlink TTI. The method
2600 may include receiving an indication of a duration of a
subsequent downlink TTI that follows the downlink TTI, wherein the
indication of the subsequent TTI duration is received during the
subsequent downlink TTI, receiving an indication of a duration of a
subsequent uplink TTI that follows the subsequent downlink TTI, and
communicating based at least in part on the indication of the
subsequent downlink TTI duration and the indication of the
subsequent uplink TTI duration. The indication of the subsequent
uplink TTI duration may be received during the subsequent downlink
TTI. The indication of the duration of the uplink TTI may indicate
that the duration of the uplink TTI is zero. The downlink TTI
duration and a subsequent downlink TTI duration may form a downlink
burst that is time division multiplexed on resources of the TDD
configured carrier. The method 2600 may include receiving a set of
TBs during the downlink TTI, where the downlink TTI comprises a
variable TTI, determining HARQ feedback for each TB of the set of
TBs, and transmitting the HARQ feedback for at least one TB of the
set of TBs during the uplink TTI. A number of TBs in the set may be
based at least in part on the duration of the downlink TTI.
[0227] The method 2600 may include receiving the set of TBs where
each TB includes at least one CB, and a number of CBs in each TB of
the set of TBs may be based on a size of the TB. The method may
also include determining HARQ feedback for a number of CBs of at
least the TB, and transmitting the HARQ feedback for at least one
CB during the uplink TTI. The method 2600 may, in some examples,
include entering a low power state during the downlink TTI or the
uplink TTI based at least in part on an absence of a grant of
resources during the downlink TTI or the uplink TTI.
[0228] FIG. 27 shows a flowchart illustrating a method 2700 for
flexible multiplexing operation for DL data in TDD systems in
accordance with various aspects of the present disclosure. The
operations of method 2700 may be implemented by a UE 115 or its
components as described with reference to FIGS. 1-8. For example,
the operations of method 2700 may be performed by the flexible
multiplexing module 510 as described with reference to FIGS. 5-8.
In some examples, a UE 115 may execute a set of codes to control
the functional elements of the UE 115 to perform the functions
described below. Additionally or alternatively, the UE 115 may
perform aspects the functions described below using special-purpose
hardware. The method 2700 may also incorporate aspects of method
2600 of FIG. 26.
[0229] At block 2705, the UE 115 may identify a downlink TTI of a
TDD configured carrier as described above with reference to FIGS.
2-4. In certain examples, the operations of block 2705 may be
performed by the TDD module 605 as described above with reference
to FIG. 6.
[0230] At block 2710, the UE 115 may receive an indication of a
duration of the downlink TTI during the downlink TTI as described
above with reference to FIGS. 2-4. In certain examples, the
operations of block 2710 may be performed by the PDFICH/PUFICH
module 620 as described above with reference to FIG. 6.
[0231] At block 2715, the UE 115 may receive an indication of a
duration of an uplink TTI that follows the downlink TTI as
described above with reference to FIGS. 2-4. The indication of the
uplink TTI duration may be received during the downlink TTI. In
certain examples, the operations of block 2715 may be performed by
the PDFICH/PUFICH module 620 as described above with reference to
FIG. 6.
[0232] At block 2720, the UE 115 may receive a set of TBs during
the downlink TTI as described above with reference to FIGS. 2-4.
The downlink TTI may include a variable TTI. In certain examples,
the operations of block 2720 may be performed by the TDD module 605
as described above with reference to FIG. 6.
[0233] At block 2725, the UE 115 may determine HARQ feedback for
each TB of the set of TBs as described above with reference to
FIGS. 2-4. A number of TBs in the set may be based at least in part
on the duration of the downlink TTI. In certain examples, the
operations of block 2725 may be performed by the TDD module 605 as
described above with reference to FIG. 6.
[0234] At block 2730, the UE 115 may transmit the HARQ feedback for
at least one TB of the set of TBs during the uplink TTI as
described above with reference to FIGS. 2-4. In certain examples,
the operations of block 2730 may be performed by the TDD module 605
as described above with reference to FIG. 6.
[0235] Thus, methods 2600 and 2700 may provide for flexible
multiplexing operation for DL data in TDD systems. It should be
noted that methods 2600 and 2700 describe possible implementations,
and that the operations and the steps may be rearranged or
otherwise modified such that other implementations are possible. In
some examples, aspects from two or more of the methods 2600 and
2700 may be combined.
[0236] FIG. 28 shows a flowchart illustrating a method 2800 for
flexible multiplexing operation for DL data in TDD systems in
accordance with various aspects of the present disclosure. The
operations of method 2800 may be implemented by a UE 115 or its
components as described with reference to FIGS. 1-8. For example,
the operations of method 2800 may be performed by the flexible
multiplexing module 510 as described with reference to FIGS. 5-8.
In some examples, a UE 115 may execute a set of codes to control
the functional elements of the UE 115 to perform the functions
described below. Additionally or alternatively, the UE 115 may
perform aspects the functions described below using special-purpose
hardware.
[0237] At block 2805, the UE 115 may identify a TDD configuration
of a carrier as described above with reference to FIGS. 2-4. In
certain examples, the operations of block 2805 may be performed by
the TDD module 605 as described above with reference to FIG. 6.
[0238] At block 2810, the UE 115 may receive a first multiplexing
format signal from a serving cell of the carrier, the first
multiplexing format signal indicating a first multiplexing
configuration of a first TTI as described above with reference to
FIGS. 2-4. In certain examples, the operations of block 2810 may be
performed by the PDFICH/PUFICH module 620 as described above with
reference to FIG. 6.
[0239] At block 2815, the UE 115 may receive a first data
transmission from the serving cell based on the first multiplexing
configuration during the first TTI as described above with
reference to FIGS. 2-4. In certain examples, the operations of
block 2815 may be performed by the receiver 505 as described above
with reference to FIG. 5.
[0240] At block 2820, the UE 115 may receive a second multiplexing
format signal from the serving cell indicating a second
multiplexing configuration of a second TTI, the second multiplexing
configuration different from the first multiplexing configuration
as described above with reference to FIGS. 2-4. In certain
examples, the operations of block 2820 may be performed by the
PDFICH/PUFICH module 620 as described above with reference to FIG.
6.
[0241] FIG. 29 shows a flowchart illustrating a method 2900 for
flexible multiplexing operation for DL data in TDD systems in
accordance with various aspects of the present disclosure. The
operations of method 2900 may be implemented by a base station 105
or its components as described with reference to FIGS. 1-4, and
9-12. For example, the operations of method 2900 may be performed
by the base station flexible multiplexing module 910 as described
with reference to FIGS. 9-12. In some examples, a base station 105
may execute a set of codes to control the functional elements of
the base station 105 to perform the functions described below.
Additionally or alternatively, the base station 105 may perform
aspects the functions described below using special-purpose
hardware. The method 2900 may also incorporate aspects of methods
2600, 2700, and 2800 of FIGS. 26-28.
[0242] At block 2905, the base station 105 may configure a TDD
carrier as described above with reference to FIGS. 2-4. In certain
examples, the operations of block 2905 may be performed by the BS
TDD module 1005 as described above with reference to FIG. 10.
[0243] At block 2910, the base station 105 may transmit a first
multiplexing format signal on the TDD carrier, the first
multiplexing format signal indicating a first multiplexing
configuration of a first TTI as described above with reference to
FIGS. 2-4. In certain examples, the operations of block 2910 may be
performed by the BS PDFICH/PUFICH module 1020 as described above
with reference to FIG. 10.
[0244] At block 2915, the base station 105 may transmit a first
data transmission on the TDD carrier to a first UE during the first
TTI based on the first multiplexing configuration as described
above with reference to FIGS. 2-4. In certain examples, the
operations of block 2915 may be performed by the transmitter 915 as
described above with reference to FIG. 9.
[0245] At block 2920, the base station 105 may transmit a second
multiplexing format signal on the TDD carrier, the second
multiplexing format signal indicating a second multiplexing
configuration of a second TTI, the second multiplexing
configuration different from the first multiplexing configuration
as described above with reference to FIGS. 2-4. In certain
examples, the operations of block 2920 may be performed by the BS
PDFICH/PUFICH module 1020 as described above with reference to FIG.
10.
[0246] Thus, methods 2600, 2700, 2800, and 2900 may provide for
flexible multiplexing operation for DL data in TDD systems. It
should be noted that methods 2600, 2700, 2800, and 2900 describe
possible implementations, and that the operations and the steps may
be rearranged or otherwise modified such that other implementations
are possible. In some examples, aspects from two or more of the
methods 2600, 2700, 2800, and 2900 may be combined.
[0247] FIG. 30 shows a flowchart illustrating a method 3000 for
feedback for variable TTI in accordance with various aspects of the
present disclosure. The operations of method 3000 may be
implemented by a UE 115 or its components as described with
reference to FIGS. 1-21. For example, the operations of method 3000
may be performed by the feedback module 1810 as described with
reference to FIGS. 18-21. In some examples, a UE 115 may execute a
set of codes to control the functional elements of the UE 115 to
perform the functions described below. Additionally or
alternatively, the UE 115 may perform aspects the functions
described below using special-purpose hardware.
[0248] At block 3005, the UE 115 may receive a plurality of TBs in
a variable downlink transmission TTI, as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3005 may be performed by the receiver 1805 as described above
with reference to FIG. 18.
[0249] At block 3010, the UE 115 may determine HARQ feedback for
each TB of the plurality of TBs, where a number of TBs in the
plurality is based on a time duration of the variable downlink TTI,
as described above with reference to FIGS. 13-17. In certain
examples, the operations of block 3010 may be performed by the HARQ
module 1905, as described above with reference to FIG. 19.
[0250] At block 3015, the UE 115 may transmit, in an uplink TTI
following the downlink TTI, the HARQ feedback for each TB, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3015 may be performed by the UL timing
determination module 1910, as described above with reference to
FIG. 19.
[0251] FIG. 31 shows a flowchart illustrating a method 3100 for
feedback for variable TTI in accordance with various aspects of the
present disclosure. The operations of method 3100 may be
implemented by a UE 115 or its components, as described with
reference to FIGS. 1-21. For example, the operations of method 3100
may be performed by the feedback module 1810 as described with
reference to FIGS. 18-21. In some examples, a UE 115 may execute a
set of codes to control the functional elements of the UE 115 to
perform the functions described below. Additionally or
alternatively, the UE 115 may perform aspects the functions
described below using special-purpose hardware. The method 3100 may
also incorporate aspects of method 3000 of FIG. 30.
[0252] At block 3105, the UE 115 may receive a plurality of TBs in
a variable downlink transmission TTI, as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3105 may be performed by the receiver 1805 as described above
with reference to FIG. 18.
[0253] At block 3110, the UE 115 may determine HARQ feedback for
each TB of the plurality of TBs, where a number of TBs in the
plurality is based at least in part on a time duration of the
variable downlink TTI, as described above with reference to FIGS.
13-17. In certain examples, the operations of block 3110 may be
performed by the HARQ module 1905 as described above with reference
to FIG. 19.
[0254] At block 3115, the UE 115 may transmit, in an uplink TTI
following the downlink TTI, the HARQ feedback for each TB, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3115 may be performed by the UL timing
determination module 1910, as described above with reference to
FIG. 19.
[0255] At block 3120, the UE 115 may determine that a maximum
number of HARQ resources for the uplink TTI is met or exceeded, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3120 may be performed by the HARQ resource
module 2005, as described above with reference to FIG. 20.
[0256] At block 3125, the UE 115 may bundle HARQ feedback for two
or more TBs of the plurality of TBs according to the maximum number
of HARQ resources, as described above with reference to FIGS.
13-17. In certain examples, the operations of block 3125 may be
performed by the feedback bundle module 2010, as described above
with reference to FIG. 20.
[0257] FIG. 32 shows a flowchart illustrating a method 3200 for
feedback for variable TTI in accordance with various aspects of the
present disclosure. The operations of method 3200 may be
implemented by a UE 115 or its components, as described with
reference to FIGS. 1-25. For example, the operations of method 3200
may be performed by the feedback module 1810, as described with
reference to FIGS. 18-22. In some examples, a UE 115 may execute a
set of codes to control the functional elements of the UE 115 to
perform the functions described below. Additionally or
alternatively, the UE 115 may perform aspects the functions
described below using special-purpose hardware. The method 3200 may
also incorporate aspects of methods 3000 and 3100 of FIGS. 30 and
31.
[0258] At block 3205, the UE 115 may receive a plurality of TBs in
a variable downlink transmission TTI, as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3205 may be performed by the receiver 1805, as described
above with reference to FIG. 18.
[0259] At block 3210, the UE 115 may determine HARQ feedback for
each TB of the plurality of TBs, where a number of TBs in the
plurality is based on a time duration of the variable downlink TTI,
as described above with reference to FIGS. 13-17. In certain
examples, the operations of block 3210 may be performed by the HARQ
module 1905, as described above with reference to FIG. 19.
[0260] At block 3215, the UE 115 may transmit, in an uplink TTI
following the downlink TTI, the HARQ feedback for each TB, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3215 may be performed by the UL timing
determination module 1910, as described above with reference to
FIG. 19.
[0261] At block 3220, the UE 115 may identify a switching interval
following the downlink TTI as described above with reference to
FIGS. 13-17. The switching interval may precede the uplink TTI.
HARQ feedback for each TB may thus be transmitted at a time based
on the identified switching interval as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3220 may be performed by the switching interval module 2015
as described above with reference to FIG. 20.
[0262] FIG. 33 shows a flowchart illustrating a method 3300 for
feedback for variable TTI in accordance with various aspects of the
present disclosure. The operations of method 3300 may be
implemented by a UE 115 or its components as described with
reference to FIGS. 1-25. For example, the operations of method 3300
may be performed by the feedback module 1810 as described with
reference to FIGS. 18-21. In some examples, a UE 115 may execute a
set of codes to control the functional elements of the UE 115 to
perform the functions described below. Additionally or
alternatively, the UE 115 may perform aspects the functions
described below using special-purpose hardware.
[0263] At block 3305, the UE 115 may transmit a first uplink TB on
resources of an uplink TTI, as described above with reference to
FIGS. 13-17. In certain examples, the operations of block 3305 may
be performed by the transmitter 1815, as described above with
reference to FIG. 18.
[0264] At block 3310, the UE 115 may receive a grant for a second
uplink TB or for a retransmission of the first uplink TB, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3310 may be performed by the receiver 1805,
as described above with reference to FIG. 18.
[0265] At block 3315, the UE 115 may determine that the grant
represents an ACK when the grant is for a second uplink TB as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3315 may be performed by the feedback
determination module 2020, as described above with reference to
FIG. 20.
[0266] At block 3320, the UE 115 may determine that the grant
represents a NACK when the grant is for a retransmission of the
first uplink TB, as described above with reference to FIGS. 13-17.
In certain examples, the operations of block 3320 may be performed
by the feedback determination module 2020, as described above with
reference to FIG. 20.
[0267] FIG. 34 shows a flowchart illustrating a method 3400 for
feedback for variable TTI in accordance with various aspects of the
present disclosure. The operations of method 3400 may be
implemented by a base station 105 or its components as described
with reference to FIGS. 1 and 22-25. For example, the operations of
method 3400 may be performed by the base station feedback module
2210 as described with reference to FIGS. 22-26. In some examples,
a base station 105 may execute a set of codes to control the
functional elements of the base station 105 to perform the
functions described below. Additionally or alternatively, the base
station 105 may perform aspects the functions described below using
special-purpose hardware.
[0268] At block 3405, the base station 105 may receive a first set
of HARQ feedback for each TB of a first plurality of TBs,
transmitted using a variable downlink TTI, from a first UE during a
first uplink TTI, as described above with reference to FIGS. 13-17.
In certain examples, the operations of block 3405 may be performed
by the first feedback reception module 2305, as described above
with reference to FIG. 23.
[0269] At block 3410, the base station 105 may receive a second set
of HARQ feedback for each TB of a second plurality of TBs from a
second UE during the first uplink TTI, as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3410 may be performed by the second feedback reception module
2310, as described above with reference to FIG. 23.
[0270] FIG. 35 shows a flowchart illustrating a method 3500 for
HARQ for variable TTI and eCC in accordance with various aspects of
the present disclosure. The operations of method 3500 may be
implemented by a base station 105 or its components as described
with reference to FIGS. 1 and 22-25. For example, the operations of
method 3500 may be performed by the base station feedback module
2210 as described with reference to FIGS. 22-25. In some examples,
a base station 105 may execute a set of codes to control the
functional elements of the base station 105 to perform the
functions described below. Additionally or alternatively, the base
station 105 may perform aspects the functions described below using
special-purpose hardware. The method 3500 may also incorporate
aspects of method 3400 of FIG. 34.
[0271] At block 3505, the base station 105 may receive a first set
of HARQ feedback for each TB of a first plurality of TBs from a
first UE during a first uplink TTI, as described above with
reference to FIGS. 13-17. In certain examples, the operations of
block 3505 may be performed by the first feedback reception module
2305, as described above with reference to FIG. 23.
[0272] At block 3510, the base station 105 may receive a second set
of HARQ feedback for each TB of a second plurality of TBs from a
second UE during the first uplink TTI, as described above with
reference to FIGS. 13-17. The first and second sets of HARQ
feedback may be CDM on a common resource. In certain examples, the
operations of block 3510 may be performed by the second feedback
reception module 2310, as described above with reference to FIG.
23.
[0273] At block 3515, the base station 105 may receive a first
PUSCH from the first UE during the first uplink TTI, the first
PUSCH and the first and second sets of HARQ feedback may be FDM, as
described above with reference to FIGS. 13-17. In certain examples,
the operations of block 3515 may be performed by the FDM PUSCH
module 2405, as described above with reference to FIG. 24.
[0274] At block 3520, the base station 105 may receive a second
PUSCH from the second UE during the first uplink TTI, the first and
second PUSCH and the first and second sets of HARQ feedback may be
FDM, as described above with reference to FIGS. 13-17. In some
cases, the base station 105 may receive GRS for each of the PUSCH
and each set of HARQ feedback in a TTI preceding the first TTI. In
certain examples, the operations of block 3520 may be performed by
the FDM PUSCH module 2405, as described above with reference to
FIG. 24.
[0275] In some examples, the base station may receive PUSCH on the
same frequency resources as several sets of HARQ feedback, where
the PUSCH and the sets of HARQ feedback are TDM. Such operations
may be performed by the TDM PUSCH module 2415, as described above
with reference to FIG. 24.
[0276] Thus, methods 3000, 3100, 3200, 3300, 3400, and 3500 may
provide for feedback for variable TTI. It should be noted that
methods 3000, 3100, 3200, 3300, 3400, and 3500 describe possible
implementation, and that the operations and the steps may be
rearranged or otherwise modified such that other implementations
are possible. In some examples, aspects from two or more of the
methods 3000, 3100, 3200, 3300, 3400, and 3500 may be combined.
[0277] The detailed description set forth above in connection with
the appended drawings describes exemplary embodiments and does not
represent all the embodiments that may be implemented or that are
within the scope of the claims. The term "exemplary" used
throughout this description means "serving as an example, instance,
or illustration," and not "preferred" or "advantageous over other
embodiments." The detailed description includes specific details
for the purpose of providing an understanding of the described
techniques. These techniques, however, may be practiced without
these specific details. In some instances, well-known structures
and devices are shown in block diagram form in order to avoid
obscuring the concepts of the described embodiments.
[0278] Information and signals may be represented using any of a
variety of different technologies and techniques. For example,
data, instructions, commands, information, signals, bits, symbols,
and chips that may be referenced throughout the above description
may be represented by voltages, currents, electromagnetic waves,
magnetic fields or particles, optical fields or particles, or any
combination thereof.
[0279] The various illustrative blocks and modules described in
connection with the disclosure herein may be implemented or
performed with a general-purpose processor, a DSP, an ASIC, an FPGA
or other programmable logic device, discrete gate or transistor
logic, discrete hardware components, or any combination thereof
designed to perform the functions described herein. A
general-purpose processor may be a microprocessor, but in the
alternative, the processor may be any conventional processor,
controller, microcontroller, or state machine. A processor may also
be implemented as a combination of computing devices (e.g., a
combination of a DSP and a microprocessor, multiple
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration).
[0280] The functions described herein may be implemented in
hardware, software executed by a processor, firmware, or any
combination thereof. If implemented in software executed by a
processor, the functions may be stored on or transmitted over as
one or more instructions or code on a computer-readable medium.
Other examples and implementations are within the scope of the
disclosure and appended claims. For example, due to the nature of
software, functions described above can be implemented using
software executed by a processor, hardware, firmware, hardwiring,
or combinations of any of these. Features implementing functions
may also be physically located at various positions, including
being distributed such that portions of functions are implemented
at different physical locations. Also, as used herein, including in
the claims, "or" as used in a list of items (for example, a list of
items prefaced by a phrase such as "at least one of" or "one or
more of") indicates an inclusive list such that, for example, a
list of [at least one of A, B, or C] means A or B or C or AB or AC
or BC or ABC (i.e., A and B and C).
[0281] Computer-readable media includes both computer storage media
and communication media including any medium that facilitates
transfer of a computer program from one place to another. A storage
medium may be any available medium that can be accessed by a
general purpose or special purpose computer. By way of example, and
not limitation, computer-readable media can comprise RAM, ROM,
electrically erasable programmable read only memory (EEPROM),
compact disk (CD) ROM or other optical disk storage, magnetic disk
storage or other magnetic storage devices, or any other medium that
can be used to carry or store desired program code means in the
form of instructions or data structures and that can be accessed by
a general-purpose or special-purpose computer, or a general-purpose
or special-purpose processor. Also, any connection is properly
termed a computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, include CD, laser disc, optical disc, digital
versatile disc (DVD), floppy disk and Blu-ray disc where disks
usually reproduce data magnetically, while discs reproduce data
optically with lasers. Combinations of the above are also included
within the scope of computer-readable media.
[0282] The previous description of the disclosure is provided to
enable a person skilled in the art to make or use the disclosure.
Various modifications to the disclosure will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other variations without departing from the scope
of the disclosure. Thus, the disclosure is not to be limited to the
examples and designs described herein but is to be accorded the
broadest scope consistent with the principles and novel features
disclosed herein.
[0283] Techniques described herein may be used for various wireless
communications systems such as code division multiple access
(CDMA), time division multiple access (TDMA), frequency division
multiple access (FDMA), orthogonal frequency division multiple
access (OFDMA), single carrier frequency division multiple access
(SC-FDMA), and other systems. The terms "system" and "network" are
often used interchangeably. A CDMA system may implement a radio
technology such as CDMA2000, Universal Terrestrial Radio Access
(UTRA), etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards.
IS-2000 Releases 0 and A are commonly referred to as CDMA2000
1.times., 1.times., etc. IS-856 (TIA-856) is commonly referred to
as CDMA2000 1.times.EV-DO, High Rate Packet Data (HRPD), etc. UTRA
includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA
system may implement a radio technology such as Global System for
Mobile Communications (GSM). An OFDMA system may implement a radio
technology such as Ultra Mobile Broadband (UMB), Evolved UTRA
(E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,
Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile
Telecommunications system (UMTS). 3GPP Long Term Evolution (LTE)
and LTE-Advanced (LTE-A) are new releases of Universal Mobile
Telecommunications System (UMTS) that use E-UTRA. UTRA, E-UTRA,
UMTS, LTE, LTE-A, and Global System for Mobile communications (GSM)
are described in documents from an organization named "3rd
Generation Partnership Project" (3GPP). CDMA2000 and UMB are
described in documents from an organization named "3rd Generation
Partnership Project 2" (3GPP2). The techniques described herein may
be used for the systems and radio technologies mentioned above as
well as other systems and radio technologies. The description
above, however, describes an LTE system for purposes of example,
and LTE terminology is used in much of the description above,
although the techniques are applicable beyond LTE applications.
* * * * *